Crystal gels useful as dental floss with improved high tear, high tensile, and resistance to high stress rupture properties

ABSTRACT

A novel dental floss and gum massager made in the form of a strand, a tape or a sheet of polymeric material, said sheet having selectively positioned multiple sized holes for inserting though and holding by the fingers of the hands. The floss provides substantially very little constriction of blood flow surrounding the fingers as the floss is held taught and the peripheral edge of the floss is being manipulated and worked by the gripping, pulling, pushing, deforming, and guilding back and forth actions of the fingers during massaging of the gums and flossing of the teeth.

ORIGINS OF INVENTION AND RELATED APPLICATIONS

This application is a continuation-in-part application of copendingapplication No. 08/719,817 filed Sep. 30, 1996, which is a CIP of Ser.No. 08/665,343 filed Jun. 17, 1996 and a CIP of Ser. No. 08/612,586filed Mar. 8, 1996 and a CIP of No. 08/581,125 filed Dec. 29, 1995, (nowPat. No. 5,962,572) and also a CIP of No. 08/581,191 filed Dec. 29,1995, now U.S. Pat. No. 5,760,117 issued Jun. 2, 1998. This applicationis also a CIP of Ser. No. 08/581,188 filed Dec. 29, 1995, now abandonedand a CIP of Ser. No. 08/288,690 filed Aug. 11, 1994, now U.S. Pat. No.5,633,286 and also a CIP of PCT/US94/07314 filed Jun. 27, 1994, and aCIP of PCT/US94/04278, filed Apr. 19, 1994. The subject matter containedin the related application is specifically incorporated herein byreference.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to dental floss and gum massager.

BACKGROUND ART

Thermoplastic elastomer SEBS gels are described in Pat. Nos. 5,334,646,5,508,334, 5,262,468, 5,153,254, 4,618,213; and 4,369,284. These gelscan be use for flossing because of their extreme softness and strength.The SEBS and SEPS triblock copolymer oil gels, however, do not havesufficient resistance to tearing when the gel is repeatedly notched ornicked by inserting and re-inserting between the teeth gaps while at thesame time applying constant tension to the floss. This failure makestriblock copolymer gels much less desirable and commercially useless andunacceptable to the flossing consumer.

DISCLOSURE OF INVENTION

1. Statement Of The Invention

I have discovered an improved dental floss and gum massager made fromnovel compositions comprising gels with improved high tear strength,improved high tensile strength, and improved resistance to high stressrupture. The improved gels can be formed into gel strands, gel tapes,and gel sheets for massaging the gum and flossing the teeth. The gelfloss can be in the form of strands and tapes when rapped around thefingers for holding, extending, and flossing are advantageously morecomfortable and less restricting to blood circulation in the fingersthan conventional dental floss. When the gel floss is in the form of asheet, it is additionally advantages for the sheet to have at least twoseparate selective sized holes at a selective distance apart for holdingsaid sheet by one or more fingers of one or both hands, said sheethaving a selected shaped peripheral sheet edge of a selective thickness,said holes being a selective distance from said edge and sized forinsertion through by at least one said finger of each hand for holdingsaid sheet and gripping, pulling, pushing, deforming, working,deforming, manipulating, folding and guilding said sheet edge formassaging the gum and flossing the teeth without substantialconstriction of blood flow of said fingers by said sheet.

I have now discovered gels with improved damage tolerance, crackpropagation resistance and tear resistance which are advantageouslysuitable for use as dental floss that are from about twice to about tentimes or better in lowering the gap insertion breaking frequency thansame rigidity gels made from triblock copolymer oil gels alone.

The invention comprises gels and articles useful as floss made frommixtures of triblock copolymers having at least one different midblockor multiblock copolymers having one, two or more different midblockswhich gels exhibit advantages of improved tensile strength, improvedtear strength (propagation resistance under tension and continuousnotching and nicking) and additionally improved resistance to highstress rupture. Such combination of properties are not found in gels ofsubstantially the same rigidity made from SEBS or SEPS triblockcopolymers alone. The gels of the present invention exhibit low set,high dimensional stability, crack, tear, craze, and creep resistanceunder tension, excellent tensile strength and high elongation, longservice life under shear, stress and strain and capable of withstandingrepeated dynamic shear, tear and stress forces, excellent processingability for cast molding, extruding, fiber forming film forming andspinning, non-toxic, nearly tasteless and odorless, soft and strong,optically clear, highly flexible, possessing elastic memory,substantially with little or no plasticizer bleedout. The gels areespecially advantageously suitable where resistance to crazing,cracking, fracturing, and catastrophic failure while under dynamicstretch tension loads in an environment where continuous or repeatedshearing, cutting, nicking, notching, lacerating, mutilating, andtearing of the gel in contact with or between other bodies (i.e.,abraded by repeated contact with another body or bodies) areencountered, such as those forces acting during dental flossing. Theresistance to tear propagation or ability to stop direct crackpropagation under dynamic tension loads is a critical factor and anadvantage of the present gels over triblock copolymer gels alone.

Still further, the tear resistance of gels floss based on typical SEBSor SEPS triblock copolymers can be improved with the addition of themultiblock copolymers or selected crystalline block copolymers formingthe gels of the invention.

Generally, the instant improved gels comprises: (I) 100 parts by weightof one or more high viscosity or selected low viscosity linear,branched, radial, star-shaped, multi-arm or branched block copolymers ormixtures of two or more such block copolymers, said block copolymershaving one or more midblocks, said midblocks comprising one or moresubstantially amorphous midblocks or one or more substantiallycrystalline polyethylene midblocks and with nil, one or more amorphousmidblocks with the proviso that when said gel comprises a mixture of oneor more of a substantially amorphous midblock block copolymers, at leastone selected substantially crystalline polyethylene midblock blockcopolymer is present in combination in said admixture; optionally incombination with a selected amount of one or more of a (II) polymer orcopolymer, and selected amounts of a plasticizing oil (III) sufficientto achieve gel rigidities of from less than about 2 gram Bloom to about1,800 gram Bloom with the proviso that said block copolymers having nilamorphous midblocks are combined with at least one block copolymerhaving at least one amorphous midblock.

As used herein, the term "gel rigidity" in gram Bloom is determined bythe gram weight required to depress a gel a distance of 4 mm with apiston having a cross-sectional area of 1 square centimeter at 23° C.

The gels comprising thermoplastic elastomer block copolymers having oneor more advantageously sufficient amount of crystalline polyethylenemidblocks of the invention are hereafter referred to as"elastic-crystalline gels" or simpler "crystal gels". The blockmidblocks of copolymers forming the crystal gels of the invention arecharacterized by sufficient crystallinity as to exhibit a meltingendotherm of at least about 40° C. as determined by DSC curve.

The various types of high viscosity or low viscosity linear, branched,radial, star-shaped or multiarm block copolymers or mixtures of two ormore such block copolymers employed in forming the crystal gels of theinvention are of the general configurations A-Z-A and (A-Z)_(n), whereinthe subscript n is two or more. In the case of multiarm block copolymerswhere n is 2, the block copolymer denoted by (A-Z)_(n) is A-Z-A. It isunderstood that the coupling agent is ignored for sake of simplicity inthe description of the (A-Z)_(n) block copolymers.

The end block segment (A) comprises a glassy amorphous polymer end blocksegment, preferably, polystyrene. The midblocks (Z) comprises one ormore midblocks of substantially poly(butylene) or -B- as further denotedbelow and substantially crystalline poly(ethylene) (simply denoted by"-E- or (E)") with or without one or more amorphous midblocks ofpoly(butylene), poly(ethylene-butylene), poly(ethylene-propylene) orcombination thereof (the amorphous midblocks are denoted by "-B- or(B)", "-EB- or (EB)", and "-EP- or (EP)" respectively or simply denotedby "-W- or (W)" when referring to one or more of the amorphous midblocksas a group) The A and Z portions are incompatible and form a two ormore-phase system consisting of sub-micron amorphous glassy domains (A)interconnected by (Z) chains. The glassy domains serve to crosslink andreinforce the structure. This physical elastomeric network structure isreversible, and heating the polymer above the softening point of theglassy domains temporarily disrupt the structure, which can be restoredby lowering the temperature.

The (I) linear, branched, radial, star-shaped, multi-arm or branchedblock copolymers block copolymers are characterized as having aBrookfield Viscosity value at 5 weight percent solids solution intoluene at 30° C. of from less than about 40 cps to about 60 cps andhigher, advantageously from about 40 cps to about 160 cps and higher,more advantageously from about 50 cps to about 180 cps and higher, stillmore advantageously from about 70 cps to about 210 cps and higher, andeven more advantageously from about 90 cps to about 380 cps and higher.

The (I) linear, branched, radial, star-shaped, multi-arm or branchedblock copolymers are characterized as having a Brookfield Viscosityvalue at 5 weight percent solids solution in toluene at 30° C. of fromabout 80 cps to about 380 cps and higher, advantageously from about 150cps to about 260 cps and higher, more advantageously from about 200 cpsto about 580 cps and higher, and still more advantageously from about100 cps to about 800 cps and higher.

The substantially amorphous block copolymers (SEBS or (SEB)_(n) withhigh butylene content and SEPS or (SEP)_(n) with high isopropylethyenecontent) forming components of mixtures of the gels of the presentinvention are of high molecular weights, but by their nature exhibitlower viscosity which advantageously range from less than about 1,000 cpto about 100 cp toluene viscosity at 10% solids at 25° C., moreadvantageously less than about 500 cp to about 100 cp, still moreadvantageously less than about 200 cp to about 90 cp or less.

The crystal gels can be made in combination with a selected amount ofone or more selected polymers and copolymers (II) includingthermoplastic crystalline polyurethane elastomers with hydrocarbonmidblocks, homopolymers, copolymers, block copolymers, polyethylenecopolymers, polypropylene copolymers, and the like described below.

The crystal gels forming the floss of the invention are also suitable inphysically interlocking or forming with other selected materials to formgel composites combinations. The materials are selected from the groupconsisting of foam, plastic, fabric, various natural and syntheticresins particles, fibers and films.

Commercial resins which can aid in adhesion to materials (plastics,glass, and metals) may be added in minor amounts to the gelatinouselastomer composition, these resins include: polymerized mixed olefins(Super Sta-tac, Betaprene Nevtac, Escorez, Hercotac, Wingtack,Piccotac), polyterpene (Zonarez, Nirez, Piccolyte, Sylvatac), glycerolester of rosin (Foral), pentaerythritol ester of rosin (Pentalyn),saturated alicyclic hydrocarbon (Arkon P), coumarone indene (Cumar LX),hydrocarbon (Picco 6000, Regalrez), mixed olefin (Wingtack), alkylatedaromatic hydrocarbon (Nevchem), Polyalphamethylstyrene/vinyl toluenecopolymer (Piccotex), polystyrene (Kristalex, Piccolastic), specialresin (LX-1035), and the like.

Furthermore, the interlocking materials with the gel of the inventionmay be made from flexible materials, such as fibers and fabrics ofcotton, flax, and silk. Other flexible materials include: elastomers,fiber-reinforced composites, mohair, and wool. Useful synthetic fibersinclude: acetate, acrylic, aremid, glass, modacrylic polyethylene,nylon, olefin, polyester, rayon, spandex, carbon, sufar,polybenzimidazole, and combinations of the above. Useful open-cellplastics include: polyamides, polyimides, polyesters, polyisocyanurates,polyisocyanates, polyurethanes, poly(vinyl alcohol), etc. Open-celledPlastic (foams) suitable for use with the compositions of the inventionare described in "Expanded Plastics and Related Products", ChemicalTechnology Review No. 221, Noyes Data Corp., 1983, and "Applied PolymerScience", Organic Coatings and Plastic Chemistry, 1975. Thesepublications are incorporated herein by reference. These include: openand non-opened cell silicone, polyurethane, polyethylene, neoprene,polyvinyl chloride, polyimide, metal, ceramic, polyether, polyester,polystyrene, polypropylene. Example of such foams are: Thanol®, Arcol®,Ugipol®, Arcel®, Arpak®, Arpro®, Arsan®, Dylite®, Dytherm®, Styrofoam®,Trymer®, Dow Ethafoam®, Ensolite®, Scotfoam®, Pyrell®, Volana®,Trocellen®, Minicel®, and the like.

The various aspects and advantages of the invention will become apparentto those skilled in the art upon consideration of the accompanyingdisclosure and the drawings.

FIGURES

FIG. 1. Representative sectional views of unexpanded gel floss of theinvention.

FIG. 2. Representative views of expanded gel floss of the invention.

FIG. 3. Representative views of expanded gel floss of the invention.

FIG. 4. Representative sectional views of various gel floss of theinvention.

MODES FOR CARRYING OUT THE INVENTION

The process of flossing involve inserting a segment of the floss intoeach gap between the teeth, moving the floss with a up-and-down motionwhile holding it tightly in tension and rubbing the sides of each toothdown to the gum line to remove plaque. The main problem withconventional dental floss, such as waxed, unwaxed nylon, spongy nylon,and teflon is that when tension is applied while inserting it betweenthe teeth, the floss can forcefully strike the gum or gum line as it isinserted through a tight teeth gap suddenly releasing with a snap,impacting the gum, producing pain, at times causing lacerations orbleeding of the gums. Another serious problem using conventional flossis that the tension applied in flossing is transferred to the flosswindings around the fingers as the floss is pulled tightly in tensionfor insertion through the gap and in tension for up-and-down flossing.With the flossing of each teeth, the cumulative tensions cause thewindings to become ever tighter. As with teflon floss, more windings areneeded to maintain tension because of natural slippage. Withoutloosening of the windings, eventually, the fingers can become extremelyuncomfortable turning blue from lack of circulation. With the use ofconventional floss and teflon less so, shredding of the floss caused bytight teeth gaps is another problem. Up to now, the process of flossingcan be an uncomfortable experience. People knowing they should floss donot or do not do so as often because of the pain and discomfortinvolved. Most dentist would not recommend young children to floss theirown teeth because serious gum damage may result due to improperflossing.

Tearing of the SEES gels has been of major concern. In general,amorphous gels such as those made form SEES and SEPS can failcatastrophically when subjected repeatedly to applied forces of highdynamic and static deformations, such as extreme compression, torsion,high tension, high elongation involving tearing and high stress ruptureconditions encountered during flossing. Additionally, the development ofcracks or crazes resulting from a large number of deformation cycles caninduce catastrophic fatigue failure of amorphous gel composites, such astears and rips between the surfaces of the amorphous gel and substratesor at the interfaces of interlocking material(s) and gel. Consequently,such amorphous gels are inadequate for the most demanding applicationsinvolving endurance at high stress and strain levels over an extendedperiod of time. Consequently, when the gel is used as floss which whencut or notched during use, the resulting catastrophic failure rendersthe gel floss useless. Therefore, the World needs a softer, gentler,more gum friendly non-lacerating dental floss.

Normally, for triblock copolymer gel floss, tensile stress, bending, ortwisting are not the cause of failure; it is the crack openings,v-notches or nicks formed on opposite sides of the gel floss as it isinserted and re-inserted into the teeth gap under continuous tensionthat develops and fails catastrophically. It is observed that triblockcopolymer gel floss break apart suddenly under tension during the firstinsertion, often times it can catastrophically break apart during thesecond or third insertion, and more often times it can catastrophicallysnap apart during the third or fourth insertions. In most instances, thetriblock copolymer gel floss fail by the fourth or fifth insertions wheninserted in a normal tight gap between normal front teeth and fail onthe first or second insertions when used between facing tight contactingamalgam molars.

The reason why this happens is possibly that at the point where the gelfloss is damaged (cut, notched or nicked) a craze front develops as morevoids form along the line perpendicular to the floss' elongateddirection (i.e., applied tension) resulting in sudden unstoppablefracturing of the bulk material ahead of the notched point causingcomplete catastrophic failure of the floss.

Consequentially, its very frustrating to attempt to floss a full set ofupper or lower teeth with triblock copolymer gel floss. It is thecomplete, unstoppable catastrophic failure of the triblock copolymer gelfloss in tension while being worked in the gap of the teeth that must beprevented in order for the gel to be useful for flossing.

Therefore, gels providing greater tear resistance under applied tensionare needed before "gels" as a class of materials can be commercializedfor use as dental floss. The gap insertion "breaking frequency" of thegel floss must be substantially lowered before the gel can be acceptableby the consumer for flossing. Breaking frequency means the number offlossing cycles to break of a floss where one cycle comprises aninsertion and extraction a floss between the teeth gap.

Block copolymers with polyethylene midblocks alone do not form suitablegels for use in making the gels of the invention. Crystalline midblockregions needs to be balanced with amorphous midblock regions in order toobtain soft, flexible and elastic gels with the desired crystallineproperties that are not found in typical SEBS and SEPS gels.

The polymers forming the gels of the invention comprisescrystalline/glassy domain/amorphous structures which are described andillustrate in copending application No. 863,794. Although the structurecan be spheroid, cylinders and plates are also within the scope of thepresent invention. Cylinder and plate structure are obtained withincreasing glassy A end blocks. From about 15-30% by weight of A blocks,the block copolymer structure is spheroid. From about 33 about 40% byweight of A blocks, the block copolymer structure becomes cylindrical;and above about 45% A blocks, the structure becomes less cylindrical andmore plate like.

In order to obtain elastic crystal gels forming the floss of theinvention, it is necessary that the selective synthesis of butadieneproduce sufficient amounts of 1,4 poly(butadiene) that on hydrogenationcan exhibit "crystallinity" in the midblocks. In order for the blockcopolymers forming the crystal gels of the invention to exhibitcrystallinity, the crystalline midblock segments must contain long runsof --CH₂ -- groups. There should be approximately at least 16 units of--(CH₂)-- in sequence for crystallinity. Only the (--CH₂ --)₄ units cancrystallize, and then only if there are at least 4 units of (--CH₂ --)₄in sequence; alternatively, the polyethylene units are denoted by[--(CH₂ --CH₂ --CH₂ --CH₂)--]₄, [(--CH₂ --)₄ ]⁴ or (--CH₂ --)¹⁶. Theamount of (--CH2--)¹⁶ units forming the (E) midblocks of the blockcopolymers comprising the crystal gels of the invention should be atleast about 20% which amount is capable of exhibiting a meltingendotherm in differential scanning calorimeter (DCS) curves.

Advantageously, the elastomer midblock segment should have acrystallinity of at least about 20% of (--CH₂ --)16 units of the totalmole % forming the midblocks of the block copolymer, more advantageouslyat least about 25%, still more advantageously at least about 30%,especially advantageously at least about 40% and especially moreadvantageously at least about 50% and higher. Broadly, the crystallinityof the midblocks should range from at least about 20% to about 60%, lessbroadly from at least about 18% to about 65%, and still less broadlyfrom at least 22% to about 70%.

The melting endotherm in DSC curves of the crystalline block copolymerscomprising at least 20% crystallinity are much higher than conventionalamorphous block copolymers. The maximum in the endotherm curves of thecrystalline block copolymers occurs at about 40° C., but can range fromgreater than about 25° C. to about 60° C. and higher. The crystallineblock copolymers forming the crystal gels of the invention can exhibitmelting endotherms (as shown by DSC) of about 25° C. to about 75° C. andhigher. More specific melting endotherm values of the crystallinemidblock block copolymers include: about 28° C., 29° C., 30° C., 31° C.,32° C., 33° C., 34° C., 35° C., 36° C., 37° C., 38° C., 39° C., 40° C.,41° C., 42° C., 43° C., 44° C., 45° C., 46° C., 47° C., 48° C., 49° C.,50° C., 51° C., 52° C., 53° C., 54° C., 55° C., 56° C., 57° C., 58° C.,59° C., 60° C., 61° C., 62° C., 63° C., 64° C., 65° C., 66° C., 67° C.,68° C., 69° C., 70° C., 71° C., 72° C., 73° C., 74° C., 75° C., 76° C.,77° C., 78° C., 79° C., 80° C., 90° C., 110° C., 120° C., and higher,whereas, the melting endotherm (DSC) for conventional amorphous midblocksegment block copolymers are about 10° C. and lower.

The melting endotherm is seen on heating and a sharp crystallizationexotherm is seen on cooling. Such midblock crystallization endothermicand exothermic characteristics are missing from DSC curves of amorphousgels. The crystallization exotherm and fusion endortherm of thecrystalline block copolymer gels of the invention are determined by ASTMD 3417 method.

Generally, the method of obtaining long runs of crystalline --(CH₂)-- isby sequential block copolymer synthesis followed by hydrogenation. Theattainment of crystal gels of the instant invention is solely due to theselective polymerization of the butadiene monomer (forming themidblocks) resulting in one or more predetermined amount of 1,4poly(butadiene) blocks followed by sequential polymerization ofadditional midblocks and hydrogenation to produce one or morecrystalline midblocks of the final block copolymers.

The crystalline block copolymers are made by sequential block copolymersynthesis, the percentage of crystallinity or (--CH₂ --)¹⁶ units shouldbe at least about (0.67)⁴ or about 20% and actual crystallinity of about12%. For example, a selectively synthesized S-EB_(n) -S copolymer havinga ratio of 33:67 of 1,2 and 1,4 poly(butadiene) on hydrogenation willresult in a midblock with a crystallinity of (0.67)⁴ or 20%. For sake ofsimplicity, when n is a subscript of -EB-, n denotes the percentage of(--CH2--)₄ units, eg, n=67 or 20% crystallinity which is the percentageof (0.67)⁴ or "(--CH₂ --)¹⁶ " units. Thus, when n=28 or 72% of (--CH₂--)₄ units, the % crystallinity is (0.72)⁴ or 26.87% crystallinityattributed to (--CH₂ --)₁₆ units, denoted by -EB₂₈ -. As a matter ofconvention, and for purposes of this specification involvinghydrogenated polybutadiene: the notation -E- denotes at least about 85%of (--CH₂ --)₄ units. The notation -B- denotes at least about 70% of[--CH₂ --CH(C₂ H₅)--] units. The notation -EB- denotes between about 15and 70% [--CH₂ --CH(C₂ H₅)--] units. The notation -EB_(n) -- denotes n %[--CH₂ --CH(C₂ H₅)--] units. For hydrogenated polyisoprene: The notation-EP- denotes about at least 90% [--CH₂ --CH(CH₃)--CH₂ CH₂ --] units. Thenotation -P- denotes about at least greater than about 70%polyisopropylethyene units.

Likewise, in order to obtain the highly amorphous midblock componentssuch as -B- forming the elastic gels of the floss of the invention, itis necessary that the selective synthesis of butadiene producesufficient amounts of vinyl or 1,2 poly(butadiene) that on hydrogenationcan exhibit "substantially amorphous polybutene" midblocks. The notation-B- denotes greater than above about 70% [--CH₂ --CH(C₂ H₅)--]_(n)polybutene units and -P- denotes greater than about 70%[--CH(CH--2CH₃)--CH₂ --]_(n) polyisopropylethyene units. Thesubstantially amorphous midblocks -EB_(n) - and -EP_(n) - of SEB_(n) Sand SEP_(n) S (or more simply denoted when n % is greater than about 70%as -B- and -P-) are more advantageously when n % is greater than about75%, still more advantageously greater than about 80%, and still moreadvantageously greater than about 85%, and even still moreadvantageously greater than about 90% or higher. Typically, highpolybutene content SEB_(n) S or simply SBS is made by adding structuremodifiers, such as ethers, which gives more 1,2 polybutadiene and afterhydrogenation, more polybutene, resulting in less crystallinity, softerblock copolymer, lower viscosity, and higher T_(g). Likewise, highpolyisopropylethyene content SEP_(n) S or simply S-P-S is made by addingstructure modifiers to give more 3,4 structure and after hydrogenation,more polyisopropylethyene, resulting in softer block copolymer, lowerviscosity, and higher T_(g).

The major advantages of SEB_(n) S and SEP_(n) S over SEBS, SEPS (when n% greater=than about 70%) is the T_(g) ofpoly(styrene-ethylene-butylene_(>70) -styrene) andpoly(styrene-ethylene/propylene-isopropylethyene_(>70) -styrene) aremuch higher; the gel rigidities are lower; and the viscosities are muchlower. More specifically, the Tg of SEBS is typically about -58° C. andthe Tg of SEPS is typically about -50° to about -60° C. Whereas, the Tgof SEB_(n) S and SEP_(n) S with high butylene content and highisopropylethyene content can be advantageously much higher of about lessthan about -40° C., advantageously -30° C. and more advantageouslyhigher of about -27° C. and higher.

It is extraordinary that where typical SEBS and SEPS gels fails toprovide adequate tensile strength, fails to provide adequate tearstrength, and fails to provide adequate resistance to high stressrupture suitable for use as dental floss, hereto unknown andunappreciated modification of the midblock structures provide heretoforeunrealizable improved higher tensile strength, improved higher tearstrength, and improved higher resistance to high stress rupture.

Theory notwithstanding, SEBS and SEPS gels fail to provide adequateproperties for use as dental floss. The following is known:

i) gels made from typical SEBS which is created from a mixture of 1, 4-and 1,2-polybutadiene to provide a random mixture of ethylene andbutylene units adequate to suppress crystallinity (as noted by Legge).Such gels can not provide adequate tear strength and lack adequateresistance to high stress rupture.

ii) gels made from typical SEPS which is created by hydrogenation ofcis-1,4-polyisoprene results in a 1:1 ethylene/propylene elastomermidblock (as noted by Legge). Such gels can not provide adequate tearstrength and lack adequate resistance to high stress rupture.

Contrary to the inferior properties of the above gels 1) and 2), thefollowing gels are found to be superior and of improved high tearstrength, improved resistance to high stress rupture and sufficientadequate tensile strength for use as dental floss:

iii) gels made from an admixture of a high crystalline ethylene contentS-E_(n) B-S block copolymer and a high butylene content S-EB_(n) -Sblock copolymer.

iv) gels made from an admixture of a high crystalline ethylene contentS-E_(n) B-S block copolymer and a high polyisopropylethyene contentS-EP_(n) -S block copolymer.

v) gels made from an admixture of a high crystalline ethylene contentS-E_(n) B-S block copolymer, a high butylene content S-EB_(n) -S blockcopolymer, and a high polyisopropylethyene content S-EP_(n) -S blockcopolymer

vi) S-E-EB_(>70) -E-S gels made by coupling S-E-EB_(>70).

vii) S-E-EP_(>70) -E-S gels made by coupling S-E-EP_(>70).

viii) gels made from linear, branched, radial, star-shaped, multi-arm orbranched block copolymers having sufficient multiple midblock componentsof high crystalline ethylene content, high butylene content, and/or highisopropylethyene content including all combinations and permutations andmixtures of such block copolymers and as further described below.

Generally, one or more (E) midblocks can be incorporated at variouspositions along the midblocks of the block copolymer's. Using thesequential process for block copolymer synthesis, The (E) midblocks canbe positioned as follows:

i) A-E-W-A

ii) A-E-W-E-A

iii) A-W-E-W-A

iv) and etc.

The highly amorphous or highly crystalline midblock components:

v) A-W-A

vi) A-E-A

The lower flexibility of block copolymer crystal gels due to (E)midblocks can be balanced by the addition of sequentially (W) midblocks.For example, the sequentially synthesized block copolymer S-E-EB-S canmaintain a high degree of flexibility due to the presence of amorphous-EB- block. The sequential block copolymer S-E-EB-B-S can maintain ahigh degree of flexibility due to the presence of amorphous -EB- and -B-midblocks. The sequential block copolymer S-E-EP-E-S can maintain a highdegree of flexibility due to the presence of -EP- midblock. Thesequential block copolymer S-E-B-S can maintain a high degree offlexibility due to the presence of the -B-, butylene midblock. ForS-E-S, where the midblock is substantially crystalline and flexibilitylow, physical blending with amorphous block copolymers such as S-EB-S,S-B-S, S-EP-S, S-EB-EP-S, (S-EP)_(n) and the like can produce moresofter, less rigid, and more flexible crystal gel.

In additional to the block copolymers S-E-EB-S and S-E-EP-S, S-E-EB-E-Scan be made by coupling S-E-EB and S-E-EP-E-S can be made by couplingS-E-EP or by making it sequentially. Multi-arm of such block copolymercan also be made.

Because of the (E) midblocks, the crystal gels forming the floss of theinvention exhibit different physical characteristics and improvementsover substantially amorphous gels including damage tolerance, improvedcrack propagation resistance, improved tear resistance producing knottytears as opposed to smooth tears, crystalline melting point of at least28° C., improved resistance to fatigue, higher hysteresis, etc.Moreover, the crystal gels forming the floss when stretched exhibitadditional yielding as shown by necking caused by stress inducedcrystallinity.

Regarding resistance to fatigue, fatigue (as used herein) is the decayof mechanical properties after repeated application of stress andstrain. Fatigue tests give information about the ability of a materialto resist the development of cracks or crazes resulting from a largenumber of deformation cycles. Fatigue test can be conducted bysubjecting samples of amorphous and crystal gels to deformation cyclesto failure (appearance of cracks, crazes, rips or tears in the gels).

Tensile strength can be determined by extending a selected gel sample tobreak as measured at 180° U bend around a 5.0 mm mandrel attached to aspring scale. Likewise, tear strength of a notched sample can bedetermined by propagating a tear as measured at 180° U bend around a 5.0mm diameter mandrel attached to a spring scale.

Various block copolymers can be obtained which are amorphous, highlyrubbery, and exhibiting minimum dynamic hysteresis:

Block copolymer S-EB-S

The monomer butadiene can be polymerized in a ether/hydrocarbon solventto give a 50/50 ratio of 1,2 poly(butadiene)/1,4 poly(butadiene) and onhydrogenation no long runs of --CH₂ -- groups and negligiblecrystallinity, ie, about (0.5)⁴ or 0.06 or 6% and actual crystallinityof about 3%. Due to the constraints of T_(g) and minimum hysteresis,conventional S-EB-S have ethylene-butylene ratios of about 60:40 with acrystallinity of about (0.6)⁴ or 0.129 or 12% and actual crystallinityof about 7.7%.

Block copolymer S-EP-S

The monomer isoprene when polymerized will produce 95% 1,4poly(isoprene)/5% 3,4 polycisoprene) and upon hydrogenation will formamorphous, rubbery poly(ethylene-propylene) midblock and no long runs of--CH₂ -- and no crystallinity.

Mixed block copolymer S-EB/EP-S

The polymerization of a 50/50 mixture of isoprene/butadiene monomers insuitable ether/hydrocarbon solvents to give equal amounts of 1,2 and 1,4poly(butadiene) on hydrogenation will produce a maximum crystallinity of(0.25)⁴ or 0.4%. The actual crystallinity would be approximately about0.2%, which is negligible and results in a good rubbery midblock.

The polymerization of a 80/20 mixture of isoprene/butadiene monomers insuitable ether/hydrocarbon solvents to give equal amounts of 1,2 and 1,4poly(butadiene) will upon hydrogenation produce a low crystallinity of(0.10)⁴ or 0.01%. The actual crystallinity would be approximately about0.006%, which is negligible and results in a good rubbery midblock.

The polymerization of a 20/80 mixture of isoprene/butadiene monomers insuitable ether/hydrocarbon solvents to give equal amounts of 1,2 and 1,4poly(butadiene) will upon hydrogenation produce a low crystallinity of(0.4)⁴ or 2.56%. The actual crystallinity would be approximately about1.53%, which is negligible and results in a good rubbery midblock.

The polymerization of a 20/80 mixture of isoprene/butadiene monomers insuitable ether/hydrocarbon solvents to give a 40:60 ratio of 1,2 and 1,4poly(butadiene) will upon hydrogenation produce a low crystallinity of(0.48)⁴ or 5.3%. The actual crystallinity would be approximately about3.2%, which is negligible and results in a good rubbery midblock.

The midblocks (Z) of one or more -E-, -B-, -EB-, or -EP- can comprisevarious combinations of midblocks between the selected end blocks (A);these include: -E-EB-, -E-EP-, -B-EP-, -B-EB-, -E-EP-E-, -E-EB-B-,-B-EP-B-, -B-EB-B-, -E-B-EB-, -E-B-EP-, -EB-EP-, -E-EB-EP-, -E-EP-EB-,-B-EB-EP-, -B-EP-EB-, -E-EP-E-EP-, -E-EP-E-EB-, -B-EP-B-EP-,-B-EB-B-EB-, -B-EB-B-EP-, -E-EB-B-EP-, -E-EP-B-EB- and the like.

The block copolymers of (A-Z-A) can be obtained by sequential synthesismethods followed by hydrogenation of the midblocks. As denoted above,abbreviations are interchangeably used, for example, (S-E-EP-S) denotespoly(styrene-ethylene-ethylene-co-propylene-styrene). Other linear blockcopolymers (denoted in abbreviations) include the following: (S-E-S),(S-E-EB-S), (S-E-EP-S), (S-B-EP-S), (S-B-EB-S), (S-E-EP-E-S),(S-E-EB-B-S), (S-B-EP-B-S), (S-B-EB-B-S), (S-E-B-EB-S), (S-E-B-EP-S),(S-EB-EP-S), (S-E-EB-EP-S), (S-E-EP-EB-S), (S-B-EB-EP-S), (S-B-EP-EB-S)and the like.

The multiblock star-shaped (or radial) copolymers (A-Z)_(n) X can beobtained by sequential synthesis methods including hydrogenation ofselected block copolymers made by polymerizing half of the blockcopolymers such as SBS or SIS and couple the halves with a couplingagent such as an organic dihalide; or couple with an agent such asSnC14, which results in star-shaped block copolymers (four branches).Coupling with divinyl benzene give block copolymers which are veryhighly branched. Radial block copolymers suitable for use in forming thecrystal gels of the present invention include: (S-E)_(n), (S-E-EB)_(n),(S-E-EP)_(n), (S-B-EP)_(n), (S-B-EB)_(n) (S-E-EP-E)_(n), (S-E-EB-B)_(n),(S-B-EP-B)_(n), (S-B-EB-B)_(n), (S-E-B-EB)_(n), (S-E-B-EP)_(n),(S-EB-EP)_(n), (S-E-EB-EP)_(n), (S-E-EP-EB)_(n), (S-B-EB-EP)_(n),(S-B-EP-EB)_(n), (S-E-EP-E-EP)_(n), (S-E-EP-E-EB)_(n), (S-EP-B-EP)_(n),(S-B-EB-B-EB)_(n), (S-B-EB-B-EP)_(n), (S-E-EB-B-EP)_(n) and counter partmultifunctional block copolymers:(R)_(n) -E-S, (R)_(n) -E-EB-S, (R)_(n)-E-EP-S, (R)_(n) -E-EP-E-S, (R)_(n) -E-EB-B-S, (R)_(n) -E-B-EB-S,(R)_(n) -E-B-EP-S, (R)_(n) -E-EB-EP-S, (R)_(n) -E-EP-EB-S and the like.In the above notation, "-E-" denotes substantially crystallinepolyethylene midblock.

The selected amount of crystallinity in the midblock should besufficient to achieve improvements in one or more physical propertiesincluding improved damage tolerance, improved crack propagationresistance, improved tear resistance, improved resistance to fatigue ofthe bulk gel and resistance to catastrophic fatigue failure of crystalgel composites, such as between the surfaces of the crystal gel andsubstrate or at the interfaces of the interlocking materials) andcrystal gel, which improvements are not found in amorphous gels atcorresponding gel rigidities.

Selected (I) linear, branched, radial, star-shaped, multi-arm orbranched block copolymers utilized in forming the crystal gels formingthe floss of the invention are characterized as having an ethylene tobutylene midblock ratio (E:B) of about 85:15 to about 65:35.Advantageously, the butylene concentration of the midblock is about 35%or less, more advantageously, about 30% or less, still moreadvantageously, about 25% or less, especially advantageously, about 20%or less. Advantageously, the ethylene to butylene midblock ratios canrange from about 89:11, 88:12, 87:13, 86:14, 85:15, 84:16, 83:17, 82:18,81:19, 80:20, 79:21, 78:22, 77:23, 76:24, 75:25, 74:26, 73:27, 72:28,71:29, 70:30, 69:31, 68:32, 67:33, 66:34 to about 65:35.

The A to Z midblock ratio of the block copolymers suitable for formingcrystal gels of the invention can range from about 20:80 to 40:60 andhigher. More specifically, the values can be 15:85, 19:81, 20:80, 21:79.22:78. 23:77, 24:76, 25:75, 26:74, 27:73, 28:72, 29:71, 30:70, 31:69,32:68, 33:67, 34:66, 35:65, 36:64, 37:63, 38:62, 39:61, 40:60, 41:59,42:58, 43:57, 44:65, 45:55, 46:54, 47:53, 48:52, 49:51, 50:50, 51:49 and52:48.

The crystal gels forming the floss can optionally comprise selectedmajor or minor amounts of one or more polymers or copolymers (II)provided the amounts and combinations are selected without substantiallydecreasing the desired properties. The polymers and copolymers can belinear, star-shaped, radial, branched, or multiarm; these including:(SBS) styrene-butadiene-styrene block copolymers, (SIS)styrene-isoprene-styrene block copolymers, low and medium viscosity(S-EB-S) styrene-ethylene-butylene-styrene block copolymers, (S-EP)styrene-ethylene-propylene block copolymers, (S-EP-S)styrene-ethylene/propylene-styrene block copolymers, (S-EP-S-EP)styrene-ethylene/propylene-styrene-ethylene/propylene) block copolymers,(S-E-EPS) styrene-ethylene-ethylene/propylene-styrene block copolymers,(SB)_(n) styrene-butadiene and (S-EB)_(n), (S-EB-S)_(n), (S-E-EP)_(n)(SEP)_(n), (SI)_(n) multi-arm, radial, branched or star-shapedcopolymers, polyethyleneoxide (EO), poly(dimethylphenylene oxide),teflon (TFE, PTFE, PEA, FEP, etc), optical clear amorphous copolymersbased on 2,2-bistrifluoromethyl-4,5-difuoro-1,3-dioxole (PDD) andtetrafluoroethylene (TFE), maleated S-EB-S block copolymer,polycarbonate, ethylene vinyl alcohol copolymer, and the like. Still,other (II) polymers include homopolymers which can be utilized in minoramounts; these include: polystyrene, polydimethylsiloxane, polyolefinssuch as polybutylene, polyethylene, polyethylene copolymers,polypropylene, and the like. Polyurethane elastomers based on saturatedhydrocarbon diols (Handlin, D., Chin. S., and Masse. M., et al."POLYURETHANE ELASTOMERS BASED ON NEW SATURATED HYDROCARBON DIOLS"Published Society of Plastics Industry, Polyurethane Division, LasVegas, Oct. 23, 1996) are also suitable for use in blending with theblock copolymers (I) used in forming the crystal gels of the invention.Such saturated hydrocarbon diols include hydroxyl terminated oligomersof poly(ethylene-butylene) (EB), poly(ethylene-propylene) (EP), -E-EB-,-E-EP-, -B-EP-, -B-EB-, -E-EP-E-, -E-EB-B-, -B-EP-B-, -B-EB-B-,-E-B-EB-, -E-B-EP-, -EB-EP-, -E-EB-EP-, -E-EP-EB-, -B-EB-EP-, -B-EP-EB-,-E-EP-E-EP-, -E-EP-E-EB-, -B-EP-B-EP-, -B-EB-B-EB-, -B-EB-B-EP-,-E-EB-B-EP-, -E-EP-B-EB- and the like. As an example, thermoplasticpolyurethane made with isocyanates and chain extenders such as TMPD andBEPD from saturated hydrocarbon diol KLP L-2203 having a hard segmentcontents of 22% exhibits clean phase separation of the hard and softsegments with glass a transition of -50° C. KLP L-2203 based TPU's canbe mixed with the crystalline block copolymers to form soft crystal gelswithin the gel rigidity ranges of the invention. High butylene contentSEBS block copolymers include Shell high molecular weight GRP6917 havinga rubber Tg of about -38° C. to about -22° C., preferably -27° C.,Toluene Viscosity at 10% solids at 25° C. of about 40 cp to about 120cp, preferably about 70 cp and styrene content of about 20 to about 40,preferably about 33, tensile strength, psi of about 4000, elongation atbreak of about 600%.

Suitable polyolefins include polyethylene and polyethylene copolymerssuch as Dow Chemical Company's Dowlex 3010, 2021D, 2038, 2042A, 2049,2049A, 2071, 2077, 2244A, 2267A; Dow Affinity ethylene alpha-olefinresin PL-1840, SE-1400, SM-1300; more suitably: Dow Elite 5100, 5110,5200, 5400, Primacor 141--XT, 1430, 1420, 1320, 3330, 3150, 2912, 3340,3460; Dow Attane (ultra low density ethylene-octene-1 copolymers) 4803,4801, 4602,

The conventional term "major" means about 51 weight percent and higher(e.g. 55%, 60%, 65%, 70%, 75%, 80% and the like) and the term "minor"means 49 weight percent and lower (e.g. 2%, 5%, 10%, 15%, 20%, 25% andthe like).

Example of (II) polymers, copolymers, and blends include: (a) Kraton G1651, G 1654X; (b) Kraton G 4600; (c) Kraton G 4609; other suitable highviscosity polymer and oils include: (d) Tuftec H 1051; (e) Tuftec H1041; (f) Tuftec H 1052; (g) Kuraray SEPS 4033; (h) Kuraray S-EB-S 8006;(i) Kuraray SEPS 2005; (j) Kuraray SEPS 2006 , and (k) blends(polyblends) of (a)-(h) with other polymers and copolymers include: (1)S-EB-S/SBS; (2) S-EB-S/SIS; (3) S-EB-S/(SEP); (4) S-EB-S/(SEB)_(n) ; (5)S-EB-S/(SEB)_(n) ; (6) S-EB-S/(SEP)_(n) ; (7) S-EB-S/(SI).sub. n; (8)S-EB-S/(SI) multiarm; (9) S-EB-S/(SEB)_(n) ; (10) (SEB)_(n) star-shapedcopolymer; (11) s made from blends of (a)-(k) with other homopolymersinclude: (12) S-EB-S/polystyrene; (13) S-EB-S/polybutylene; (14)S-EB-S/polyethylene; (14) S-EB-S/polypropylene; (16) SEP/S-EB-S, (17)SEP/SEPS, (18) SEP/SEPS/SEB, (19), SEPS/S-EB-S/SEP, (20), SEB/S-EB-S(21), EB-EP/S-EB-S (22), S-EB-S/EB (23), S-EB-S/EP (24), (25) (SEB)_(n)s, (26) (SEP)_(n), (27) Kuraray 2007 (SEPS), (28) Kuraray 2002, (SEPS),(29) Kuraray 4055 (S-EB-EP-S) (30) Kuraray 4077 (S-EB-EP-S) (31) Kuraray4045 (S-EB-EP-S) (32) (S-EB-EP)_(n), (33) (SEB)_(n), (34) EPDM, (35)EPR, (36) EVA, (37) coPP, (38) EMA, (39) EEA, (40) DuPont Teflon AFamorphous fluoropolymers, (41) Dow polydimethylsiloxane, (42) maleatedS-EB-S (maleation level 2-30%), (43) (EP)_(n), (44) Kraton GRP6918 andthe like.

Representative examples of commercial elastomers that can be combinedwith the block copolymers (I) described above include: Shell KratonsD1101, D1102, D1107, D1111, D1112, D1113X, D1114X, D1116, D1117, D1118X,D1122X, D1125X, D1133X, D1135X, D1184, D1188X, D1300X, D1320X, D4122,D4141, D4158, D4240, G1650, G1652, G1657, G1701X, G1702X, G1726X,G175OX, G1765X, FG19O1X, FG1921X, D2103, D2109, D2122X, D3202, D3204,33226, D5298, D5999X, D7340, G1650, G1651, G1652, G4609, G4600, G1654X,G2701, G2703, G2705, G1706, G2721X, G7155, G7430, G7450, G7523X, G7528X,G7680, G7705, G7702X, G7720, G7722X, G7820, G7821X, G7827, G7890X,G7940, G1730M, FG19OlX and FG1921X. Kuraray's SEP, SEPS, S-EB-S,S-EB-EP-S Nos. 1001, 1050, 2027, 2003, 2006, 2007, 2008, 2023, 2043,2063, 2050, 2103, 2104, 2105, 4033, 4045, 4055, 4077, 8004, 8006, 8007and the like.

The amorphous S-EB-S and (S-EB)n (II) copolymers can have a broad rangeof styrene to ethylene-butylene ratios (S:EB) of about 20:80 or less toabout 40:60 or higher. The S:EB weight ratios can range from lower thanabout 20:80 to above about 40:60 and higher.

The Brookfield Viscosity of a 5 weight percent solids solution intoluene at 30° C. of 2006, 4045, 4055, 4077 typically range about 20-35,about 25-150, about 60-150, about 200-400 respectively. TypicalBrookfield Viscosities of a 10 weight percent solids solution in tolueneat 30° C. of 1001, 1050, 2007, 2063, 2043, 4033, 2005, 2006, are about70, 70, 17, 29, 32, 50, 1200, and 1220 respectively. Typical BrookfieldViscosity of a 25 weight percent solids solution in toluene at 25° C. ofKraton D1101, D1116, D1184, D1300X, G1701X, G1702X are about 4000, 9000,20000, 6000, 50000 and 50000 cps respectively. Typical BrookfieldViscosity of a 10 weight percent solids solution in toluene at 25° C. ofG1654X is about 370 cps.

Suitable block copolymers (II) and their typical viscosities are furtherdescribed. Shell Technical Bulletin SC:1393-92 gives solution viscosityas measured with a Brookfield model RVT viscometer at 25° C. for KratonG 1654X at 10% weight in toluene of approximately 400 cps and at 15%weight in toluene of approximately 5,600 cps. Shell publication SC:68-79gives solution viscosity at 25° C. for Kraton G 1651 at 20 weightpercent in toluene of approximately 2,000 cps. When measured at 5 weightpercent solution in toluene at 30° C., the solution viscosity of KratonG 1651 is about 40. Examples of high viscosity S-EB-S triblockcopolymers includes Kuraray's S-EB-S 8006 which exhibits a solutionviscosity at 5 weight percent at 30° C. of about 51 cps. Kuraray's 2006SEPS polymer exhibits a viscosity at 20 weight percent solution intoluene at 30° C. of about 78,000 cps, at 5 weight percent of about 27cps, at 10 weight percent of about 1220 cps, and at 20 weight percent78,000 cps. Kuraray SEPS 2005 polymer exhibits a viscosity at 0.5 weightpercent solution in toluene at 30° C. of about 28 cps, at 10 weightpercent of about 1200 cps, and at 20 weight percent 76,000 cps. Othergrades of S-EB-S, SEPS, (SEB)_(n) (SEP)_(n) polymers can also beutilized in the present invention provided such polymers exhibits therequired high viscosity. Such S-EB-S polymers include (high viscosity)Kraton G 1855X which has a Specific Gravity of 0.92, BrookfieldViscosity of a 25 weight percent solids solution in toluene at 25° C. ofabout 40,000 cps or about 8,000 to about 20,000 cps at a 20 weightpercent solids solution in toluene at 25° C..

The styrene to ethylene and butylene (S:EB) weight ratios for the Shelldesignated polymers can have a low range of 20:80 or less. Although thetypical ratio values for Kraton G 1651, 4600, and 4609 are approximatelyabout 33:67 and for Kraton G 1855X approximately about 27:73, Kraton G1654X (a lower molecular weight version of Kraton G 1651 with somewhatlower physical properties such as lower solution and melt viscosity) isapproximately about 31:69, these ratios can vary broadly from thetypical product specification values. In the case of Kuraray's S-EB-Spolymer 8006 the S:EB weight ratio is about 35:65. In the case ofKuraray's 2005 (SEPS), and 2006 (SEPS), the S:EP weight ratios are 20:80and 35:65 respectively. The styrene to ethylene-ethylene/propylene(S:EB-EP) ratios of Kuraray's SEPTON 4045, 4055, and 4077 are typicallyabout 37.6, 30, 30 respectively. More typically the (S:EB-EP) and (S:EP)ratios can vary broadly much like S:EB ratios of S-EB-S and (SEB)_(n)from less than 19:81 to higher than 51:49 (as recited above) arepossible. It should be noted that multiblock copolymers including SEPTON4045, 4055, 4077 and the like are described in my cited copending parentapplications and are the subject matter of related inventions.

The block copolymers (II) such as Kraton G 1654X having ratios of 31:69or higher can be used and do exhibit about the same physical propertiesin many respects to Kraton G 1651 while Kraton G 1654X with ratios below31:69 may also be use, but they are less advantageous due to theirdecrease in the desirable properties of the final gel.

Plasticizers (III) particularly advantageous for use in practicing thepresent invention are will known in the art, they include rubberprocessing oils such as paraffinic and naphthenic petroleum oils, highlyrefined aromatic-free paraffinic and naphthenic food and technical gradewhite petroleum mineral oils, and synthetic liquid oligomers ofpolybutene, polypropene, polyterpene, etc. The synthetic series processoils are high viscosity oligomers which are permanently fluid liquidnonolefins, isoparaffins or paraffins of moderate to high molecularweight.

The amount of plasticizing oil (III) sufficient to achieve gelrigidities of from less than about 2 gram Bloom to about 1,800 gramBloom range from less than about 250 to about 3,000 parts by weight of aplasticizing oil.

Examples of representative commercially available plasticizing oilsinclude Amoco® polybutenes, hydrogenated polybutenes, polybutenes withepoxide functionality at one end of the polybutene polymer, liquidpoly(ethylene/butylene), liquid hetero-telechelic polymers ofpoly(ethylene/butylene/styrene) with epoxidized polyisoprene andpoly(ethylene/butylene) with epoxidized polyisoprene: Example of suchpolybutenes include: L-14 (320 Mn), L-50 (420 Mn), L-100 (460 Mn), H-15(560 Mn), H-25 (610 Mn), H-35 (660 Mn), H-SO (750 Mn), H-100 (920 Mn),H-300 (1290 Mn), L-14E (27-37 cst @100° F. Viscosity), H-300E (635-690cst @210° F. Viscosity), Actipol E6 (365 Mn), E16 (973 Mn), E23 (1433Mn), Kraton L-2203 and Kraton L-1203, EKP-206, EKP-207, HPVM-2203 andthe like. Example of various commercially oils include: ARCO Prime (55,70, 90, 200, 350, 400 and the like), Duraprime and Tufflo oils (6006,6016, 6016M, 6026, 6036, 6056, 6206, etc) , other white mineral oilsinclude: Bayol, Bernol, American, Blandol, Drakeol, Ervol, Gloria,Kaydol, Litetek, Lyondell (Duraprime 55, 70, 90, 200, 350, 400, etc),Marcol, Parol, Peneteck, Primol, Protol, Sontex, Witco brand white oilsincluding RR-654-P and the like. Generally, plasticizing oils withaverage molecular weights less than about 200 and greater than about 700may also be used (e.g., H-300 (1290 Mn)).

Comparisons of oil extended S-EB-S triblock copolymers have beendescribed in Shell Chemical Company Technical Bulletin SC:1102-89 (April1989) "KRATON® THERMOPLASTIC RUBBERS IN OIL GELS" which is incorporatedherein by reference.

The crystal gels forming the floss can be made non-adhearing,non-sticking, (non-tacky), by incorporating an advantage amount ofstearic acid (octadecanoic acid), metal stearates (e.g., calciumstearate, magnesium stearate, zinc stearate, etc.), polyethylene glycoldistearate, polypropylene glycol ester or fatty acid, andpolytetramethylene oxide glycol disterate, waxes, stearic acid andwaxes, metal stearate and waxes, metal stearate and stearic acid. Theuse of stearic acid alone do not reduce tack. The amount of stearic acidis also important. As an example, ratio of 200 grams stearic acid to2,000 gram of S-EB-S (a ratio of 0.1) will result in spotted tackreduction on the surface of the gel. A ratio of 250 to 2,000 will resultin spotted crystallized stearic acid regions on the surface of the gelor spotted tack reduction. A ratio of 300 to 2,000 will result incomplete tack reduction with large stearic acid crystallized regions onthe surface of the gel. When microcrystalline waxes are incorporatedtogether with stearic acid, the crystallization of stearic acidcompletely disappears from the surface of the gel. For example excellentresult is achieved with 200 grams of stearic acid, 150 grams ofmicrocrystalline wax and 2,000 grams of S-EB-S. The same excellentresult is achieved when S-EB-S is adjusted to 3,000 grams, 4,000 grams,etc. The same result is achieved with (I) copolymers as well as incombination with polymers (II) such as SEPS, S-EB-EP-S, (S-EB-EP)_(n),(SEB)_(n), (SEP)_(n) polymers. Moreover, when about 50 grams oftetrakistmethylene 3-(3'5'di-tertbutyl-4"-hydroxyphenyl) propionate)methane is use as a tack reducing blooming agent, tack is completelyremoved from the surface of the gel after two to three weeks ofblooming.

The crystal gels forming the floss can also contain useful amounts ofconventionally employed additives such as stabilizers, antioxidants,antiblocking agents, colorants, fragrances, flame retardants, flavors,other polymers in minor amounts and the like to an extend not affectingor substantially decreasing the desired properties. Additives useful inthe crystal gel of the present invention include: tetrakis(methylene3-(3',5'-di-tert-butyl-4"-hydroxyphenyl) propionate) methane, octadecyl3-(3",5"-di-tertbutyl-4"-hydroxyphenyl) propionate,distearyl-pentaerythritol-diproprionate, thiodiethylenebis-(3,5-ter-butyl-4-hydroxy) hydrocinnamate,(1,3,5-trimethyl-2,4,6-tris[3,5-di-tert-butyl-4-hydroxybenzyl] benzene),4,4"-methylenebis(2,6-di-tert-butylphenol), steraric acid, oleic acid,stearamide, behenamide, oleamide, erucamide, N,N"-ethylenebisstearamide,N,N"-ethylenebisoleamide, sterryl erucamide, erucyl erucamide, oleylpalmitamide, stearyl stearamide, erucyl stearamide, calcium sterate,other metal sterates, waxes (e.g., polyethylene, polypropylene,microcrystalline, carnauba, paraffin, montan, candelilla, beeswax,ozokerite, ceresine, and the like), teflon (TFE, PTFE, PEA, FEP, etc),polysiloxane, etc. The crystal gel can also contain metallic pigments(aluminum and brass flakes), TiO2, mica, fluorescent dyes and pigments,phosphorescent pigments, aluminatrihydrate, antimony oxide, iron oxides(Fe₃ O₄, --Fe₂ O₃, etc.), iron cobalt oxides, chromium dioxide, iron,barium ferrite, strontium ferrite and other magnetic particle materials,molybdenum, silicones, silicone fluids, lake pigments, aluminates,ceramic pigments, ironblues, ultramarines, phthalocynines, azo pigments,carbon blacks, silicon dioxide, silica, clay, feldspar, glassmicrospheres, polymer microspheres, barium ferrite, wollastonite and thelike. The report of the committee on Magnetic Materials, PublicationNMAB-426, National Academy Press (1985) is incorporated herein byreference.

The crystal gels denoted as "G" can be physically interlocked with aselected material denoted as "M" to form composites as denoted forsimplicity by their combinations G_(n) M_(n), G_(n) M_(n) G_(n) l M_(n)G_(n) M_(n), M_(n) G_(n) G_(n), G_(n) G_(n) M_(n), M_(n) M_(n) M_(n)G_(n), M_(n) M_(n) M_(n) G_(n) M_(n), M_(n) G_(n) G_(n) M_(n), G_(n)M_(n) G_(n) G_(n), G_(n) M_(n) M_(n) G_(n), G_(n) M_(n) M_(n) G_(n),G_(n) G_(n) M_(n) M_(n), G_(n) G_(n) M_(n) G_(n) M_(n), G_(n) M_(n)G_(n) G_(n), G_(n) G_(n) M_(n), G_(n) M_(n) G_(n) M_(n) M_(n), M_(n)G_(n) M_(n) G_(n) M_(n) G_(n), G_(n) G_(n) M_(n) M_(n) G_(n), G_(n)G_(n) M_(n) G_(n) M_(n) G_(n), and the like or any of their permutationsof one or more G_(n) with M_(n) and the like, wherein when n is asubscript of M, n is the same or different selected from the groupconsisting of foam, plastic, fabric, metal, concrete, wood, glass,ceramics, synthetic resin, synthetic fibers or refractory materials andthe like; wherein when n is a subscript of G, n denotes the same or adifferent gel rigidity of from about 2 gram to about 1,800 gram Bloom).The gels of the composites can be formed in combination with a selectedamount of at least one polymer or copolymer selected from the groupconsisting of poly(styrene-butadiene-styrene), poly(styrene-butadiene),poly(styrene-isoprene-styrene), poly(styrene-isoprene),poly(styrene-ethylene-propylene), low viscositypoly(styrene-ethylene-propylene-styrene), low viscositypoly(styrene-ethylene-butylene-styrene),poly(styrene-ethylene-butylene), polystyrene, polybutylene,poly(ethylene-propylene), poly(ethylene-butylene), polyproplyene, orpolyethylene, wherein said selected copolymer is a linear, branched,multiarm, or star shaped copolymer are useful as dental floss.

The crystal gels forming the floss are prepared by blending together thecomponents including other additatives as desired at about 23° C. toabout 100° C. forming a paste like mixture and further heating saidmixture uniformly to about 150° C. to about 200° C. until a homogeneousmolten blend is obtained. Lower and higher temperatures can also beutilized depending on the viscosity of the oils and amounts ofmultiblock copolymers (I) and polymer (II) used. These components blendeasily in the melt and a heated vessel equipped with a stirrer is allthat is required. Small batches can be easily blended in a test tubeusing a glass stirring rod for mixing. While conventional large vesselswith pressure and/or vacuum means can be utilized in forming largebatches of the instant crystal gels in amounts of about 40 lbs or lessto 10,000 lbs or more. For example, in a large vessel, inert gases canbe employed for removing the composition from a closed vessel at the endof mixing and a partial vacuum can be applied to remove any entrappedbubbles. Stirring rates utilized for large batches can range from aboutless than 10 rpm to about 40 rpm or higher.

The crystal gel articles can be formed by blending, injection molding,extruding, spinning, casting, dipping and other conventional methods.For example, Shapes having various cross-section can be extruded. Thecrystal gels can also be formed directly into articles or remelted inany suitable hot melt applicator and extruded into shaped articles andfilms or spun into threads, strips, bands, yarns, or other shapes. Withrespect to various shapes and yarn, its size are conventionally measuredin denier (grams/9000 meter), tex (grams/1000 meter), and gage (1/2.54cm). Gage, tex, denier can be converted as follows:tex=denier/9=specific gravity (2135/gage), for rectangular crosssection, tex=specific gravity (5806×103) (th) (w)/9, where th is thethickness and w the width of the strip, both in centimeters. Generaldescriptions of (1) block copolymers, (2) elastomeric fibers andconventional (3) gels are found in volume 2, starting at pp. 324-415,volume 6, pp 733-755, and volume 7, pp. 515 of ENCYCLOPEDIA OF POLYMERSCIENCE AND ENGINEERING, 1987 which volumes are incorporated herein byreference.

Not only do the crystal gels forming the floss have all the desirablecombination of physical and mechanical properties substantially similarto high viscosity amorphous S-EB-S gels such as high elongation at breakof at least 1,600%, ultimate tensile strength of about 8×10⁵ dyne/cm²and higher, low elongation set at break of substantially not greaterthan about 2%, substantially about 100% snap back when extended to1,200% elongation, and a gel rigidity of substantially from about 2 gramto about 1,800 gram Bloom and higher, the crystal gels of the presentinvention exhibit improved tear resistance and resistance to fatigue notobtainable from amorphous S-EB-S or S-EP-S gels at corresponding gelrigidities.

The crystal gels forming the floss of the present invention exhibit oneor more of the following properties. These are: (1) tensile strength ofabout 8×10⁵ dyne/cm² to about 10⁷ dyne/cm² and greater; (2) elongationof less than about 1,600% to about 3,000% and higher; (3) elasticitymodules of about 10⁴ dyne/cm² to about 10⁶ dyne/cm² and greater; (4)shear modules of about 10⁴ dyne/cm² to about 10⁶ dyne/cm² and greater asmeasured with a 1, 2, and 3 kilogram load at 23° C.; (5) gel rigidity ofabout less than about 2 gram Bloom to about 1,800 gram Bloom and higheras measured by the gram weight required to depress a gel a distance of 4mm with a piston having a cross-sectional area of 1 square cm at 23° C.;(6) tear propagation resistance greater than the tear resistance ofamorphous S-EB-S gels at corresponding gel rigidities; (7) resistance tofatigue greater than the fatigue resistance of amorphous S-EB-S gels atcorresponding gel rigidities; (8) and substantially 100% snap backrecovery when extended at a crosshead separation speed of 25 cm/minuteto 1,200% at 23° C. Properties (1), (2), (3), and (6) above are measuredat a crosshead separation speed of 25 cm/minute at 23° C.

The crystal gels can be formed in any shape; the original shape can bedeformed into another shape (to contact a regular or regular surface) bypressure and upon removal of the applied pressure, the composition inthe deformed shape will recover back to its original shape.

For purposes of dental flossing, while flossing between two closelyadjacent teeth, especially between two adjacent teeth with substantialcontact points and more especially between two adjacent teeth withsubstantial amalgam alloy metal contact points showing no gap betweenthe teeth, it is critical that the crystal gel resist tearing, shearing,and crazing while being stretched to a high degree in such situations.For example, dental crystal gel floss can take the form of a disk wherethe segments of the circumference of the disk is stretched for flossingbetween the teeth. Other shaped articles suitable for flossing includethreads, strips, yarns, tapes, etc., mentioned above.

In all cases, the tear strength of crystal gels are higher than that ofamorphous gels. For example, the crystal gels made from high viscosityS-E-EB-S and S-E-EP-S copolymers are resistant to tearing when underhigh stress or shear than high viscosity typical S-EB-S and S-EP-Scopolymer gels.

In order for gels to be useful as a dental floss, it must overcome thedifficult barriers of high shearing and high tearing under extremeelongation and tension loads. The difficulties that the gels mustovercome during flossing can be viewed as follows: during the action offlossing, the gel is stretched from no less than about 200% to about1,100% or higher, the gel floss is deformed as it is pulled down withtearing action between the contacting surfaces of the teeth, then, thewedge of gel floss is sheared between the inner contacting surfaces ofthe teeth, and finally, the elongated wedged of gel floss is pulledupwards and out between the surfaces of the teeth. The forcesencountered in the act of flossing are: tension, shearing, tearing underextreme tension.

This invention advances the flossing art by providing strong, soft, andextreme tear resistant gels made from multiblock copolymers which gelsare substantially as soft as the gums surrounding the teeth.

Gel floss formed from the gels has many advantages over conventionaldental floss such as regular and extra fine waxed and unwaxed nylonfloss, spongy nylon fiber floss, and waxed and unwaxed expanded andunexpended teflon floss. Such conventional floss are not recommended foruse by children, since a slip or sudden snap in forcing the flossbetween the teeth may cause injury to the gums which often times resultsin bleeding. For sensitive gums and inflamed gums which has become redand puffy, it is difficult to floss at, near, and below the gumline. Thesoft gel floss with softness substantially matching the softness of thegums are of great advantage for use by children and for flossing teethsurrounded by sensitive and tender gums.

The shear resistant characteristics of the gels can be indirectlydetermined by subjecting the gel to the shear forces of a pair oftwisting strings and the resulting inward pulling forces of the twistingstrings can be directly read off of a spring scale. As a pair of stringsare gradually twisted, typical values will range from less than onepound to fifty pounds and greater. As the string is being twisted(simulating increased shearing forces), the measured pulling forces canrange from a low value of 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30,31 . . . to values of 40, 50, 60, 70, 80 pounds and greater.

Gel material of low strength can not resist the tremendous shearingaction of the twisting strings. The twisting action of the strings canexhibit a first order twist, a second order twist, or higher ordertwists. A first order twist refers to one or more twists of a pair ofstrings (i.e., a pair of strings when twisted together forms a smalltight binding helix). A second order twist refers to one or more largebinding helixes build up by a pair of strings that have been twistedbeyond the maximum number of twist which normally produce small tightbinding helixes of the first order kind. Similarly, a third order twistrefers to a much larger tightly binding helix build up by the maximumnumber of second order twists produced by the pair of twisting strings.The third order twist may be manifested by the appearance of a branch oftwo or more twist of the first order twisting strings.

The order of twisting will increase (from a one, two, three, and higherorder twist) until the rubber band breaks. Likewise, a looped stringwith one end attached to a spring scale and the other end attached to afixed anchor can be twisted into a first, second, third, and higherordered twist state. This method can be utilized to directly measure theforce generated for each ordered twist states. The static forcegenerated by twisting a string on a spring scale is a way of determiningthe shear force generated in the shearing action of forcing the gelfloss between two closely contacting teeth when flossing.

In considering dental flossing criteria, one or more of the followingconditions can be regarded as critical factors for dental flossing gels.

SHEAR RESISTANT CRITERIA

For the gels to be considered useful for flossing, the gels, critically,should withstand a twisting string shearing force of at least about 5Kg, more advantageously at least about 8 Kg, and still moreadvantageously at least about 10 Kg of inward pulling force of a pair oftwisting strings measured directly on a spring scale.

FLOSSING CYCLE CRITERIA

For the gels to be considered useful for flossing, the gels, critically,should advantageously be able to perform at least 4 flossing cycles,more advantageously 8 cycles, and still more advantageously of about 20cycles without breaking apart when a 3.0 mm diameter gel strand istested on a set of simulated upper front teeth fully contacting under auniform spring load of (0.9027 Kg) two pounds. The simulated upper frontteeth comprises two small stainless steel rollers (3/8" dia.) facinglengthwise parallel and forced together so as to form a contact lengthof 1/2 inches under a spring load of two pounds as measured by a Entran®model ELO-200-4 load cell adjusted by a straight micrometer at roomtemperature.

GEL STRENGTH CRITERIA

For the gels to be considered useful for flossing, the gels, critically,should advantageously exhibit a tensile strength of at least 5 Kg/cm²(when extended to break as measured at 180° U bend around a 5.0 mmmandrel attached to a spring scale) and more advantageously at least 8Kg/cm², and still more advantageously of about 10 Kg/cm² and higher. Thehigh and gels useful as dental floss can exhibit tensile strengths atbreak of at least 20 Kg/cm², more advantageously of at least 40 Kg/cm²,and exceptionally more advantageously at least 60 Kg/cm². Typically, thetensile strengths range from about 20 Kg/cm² to about 110 Kg/cm2 andhigher, more typically from about 30 Kg/cm² to 80 Kg/cm² and higher,especially more typically from about 40 Kg/cm² to about 90 Kg/cm² andhigher, and exceptionally typically from about 50 Kg/cm² to about 100Kg/cm² and higher.

PROPAGATING TEAR CRITERIA

As a minimum, for the Gels to be considered useful for flossing, thegels, critically, should advantageously exhibit a propagating tear force(when propagating a tear as measured at 180° U bend around a 5.0 mmdiameter mandrel attached to a spring scale) of at least about 1 Kg/cm,more advantageously at least 2 Kg/cm, and still more advantageously ofabout 3 Kg/cm and higher. The gels useful as dental floss can exhibittear strengths of at least 4 Kg/cm and higher, more advantageously of atleast 6 Kg/cm and higher, exceptionally more advantageously of at least8 Kg/cm and higher. Typically, the tear propagation strength can rangefrom about 5 Kg/cm to about 20 Kg/cm and higher, more typically fromabout less than 5 Kg/cm to about 25 Kg/cm and higher, especially moretypically form about less than 6 Kg/cm to about 30 Kg/cm and higher, andexceptionally more typically from about less than 8 Kg/cm to about 35Kg/cm and higher.

For the Gels to be considered useful for flossing, the gels, critically,should advantageously exhibit a propagating tension tear force (when acylindrical sample is notched and a tear is initiated at the notchedarea and propagated past its maximum cylindrical diameter by length-wisestretching of the cylindrical sample) of at least about 1 Kg/cm, moreadvantageously at least 2 Kg/cm, and still more advantageously of about4 Kg/cm and higher. The extreme tear resistant gels typically willexhibit even higher tension tear values.

RIGIDITY CRITERIA

The rigidities of the extreme tear resistant useful for flossing canadvantageously range from about 350 gram to about 1,800 gram Bloom, moreadvantageously from about 400 gram to about 1,500 gram Bloom, especiallymore advantageously from about 450 gram to about 1,200 gram Bloom, stillmore advantageously from about 450 gram to about 1,000 gram Bloom, andless advantageously at values of greater than 1,800 gram Bloom.

HIGH STRESS RUPTURE CRITERIA

This is demonstrated by forming very soft gel samples, for example 100parts copolymer to 800 parts plasticizing oil. The soft gel is made in a16 mm×150 mm test tube, the gel cylinder is cut or notched at one pointabout its cross-section and gripped lengthwise tightly in the left handabout this cross-section point and a length of exposed gel is grippedlengthwise around the adjacent cross-section point tightly by the righthand as close to the left hand as possible without stretching. With thetwo hands gripping the gel sample's cross-section about the notchedpoint, the hands are moved in opposite directions to tear apart the gelsample at the cross-section point. The high shearing action by thegripping hands is done at the fastest speed possible as can be performedby human hands. Using this demonstration, the crystal gels will noteasily break or tear completely apart, whereas, amorphous S-EB-S andS-EP-S gels break or tears apart easily. Likewise the various crystalgels of the invention described herein are tested and found to be moreresistant to high stress rupture than typical SEBS and SEPS gels. Forfloss, the improved resistance high stress rupture is essential.

In general, as a minimum, the flossing gels should exhibit severalcritical properties, including advantageously the ability to:

(1) withstand a shearing force of at least about 5 Kg under the stringtwisting test described above,

(2) perform at least 4 flossing cycles without breaking apart whentested on a set of simulated upper front teeth fully contacting under auniform spring load of two pound,

(3) exhibit a tensile strength of at least 5 Kg/cm² and higher,

(4) exhibit a propagating tear force at 180° U bend tear test of atleast about 1 Kg/cm, and

(5) exhibit a propagating tension tear force (on a notched cylindricalsample) of at least about 1 Kg/cm.

For use as a dental floss, the gel is made (by extruding, spinning,casting, etc) as a continuous gel strand, the gel strand can be in theshape of a fiber of a selected diameter (from less than about 0.15 toabout 5.0 mm and greater) as a continuous tape having a selected widthand thickness (less than 0.10 mm thin to about 5.0 mm and thicker) or inany desired shape suitable for flossing. The fiber, tape or a selectedshape is then cut to a desired length, rolled up and placed into adispenser suitable for containing and dispensing a measured use amountof gel floss. The continuous fiber and tape can be partly cut or notchedfor measured single or multiple use. When the floss is pulled from thedispenser to a point showing the notched or cut mark on the length ofgel floss, the lid is pushed down on the gel floss nipping it andallowing the floss to be further pulled and separated at the notched orcut point. Additionally, a suitable floss dispenser containing ameasured length of gel floss can be fitted with a cutting edge attachedto its lid or on its body and the uncut and un-notched gel floss can bedispensed from the dispensing container and cut at the desired measureduse length by pressing close the dispenser cutting edge down on thefloss so as to nip and cut the gel or by simply closing the dispenserlid or running the gel along the cutting edge on the dispenser bodyseparating a useful length of gel floss.

In practice, typically during flossing, a gel strand will under govarious deformations, some of these deformations can be measured,including original shape, extended shape under tension, nipping force,and nipped deformation under a measured force and width. Typically, anyshaped gel strand can be used for flossing, a square cross-section, acircular cross-section, a rectangular cross-section, round, oval, etc.For example, a 2.35 mm diameter strand when extended under a force of2.5 kg can be nipped down to 0.14 mm thickness (along a 3 mm uniformwidth of its cross-section) by a force of 0.9072 Kg (2.0 pound force), areduction of 16.78:1; a 1.89 mm diameter strand when extended under aforce of 2.5 kg can be nipped down to 0.14 mm thickness by a force of0.9072 Kg (2.0 pound force), a reduction of 13.5:1; a 2.75 mm diameterstrand when extended under a force of 2.5 kg can be nipped down to 0.19mm thickness by a force of 0.9072 Kg (2.0 pound force), a reduction of14.4:1; and a 2.63 mm diameter strand when extended under a force of 2.5kg can be nipped down to 0.19 mm thickness by a force of 0.9072 Kg (2.0pound force), a reduction of 13.8:1, the cross-section of the gel flosscan be reduced to any degree by stretching and nipping (from less thanabout 1% to about 1,600% and higher). Advantageously, a gel having therequired strength, tear resistance, gel rigidity, and othercharacteristics described can be formed into a floss of any selectedcross-section and thickness provided the floss is capable of beingstretched when flossing under tension without breaking. Typically thestretching or pulling force is from about less than 0.1 Kg to about 3 Kgand higher. The cross-section of the strand of gel floss should becapable of being nipped by a 0.9027 Kg (2 pounds) force applied across awidth of 3 mm from its original cross-sectional dimensions to a nippedthickness of about 3.0 mm to about 0.02 mm and lower, moreadvantageously from about 2.5 mm to about 0.04 mm and lower, still moreadvantageously from about 2.0 mm to about 0.08 mm and lower; especiallyadvantageously from about 1.5 mm to about 0.15 mm and lower; especiallymore advantangeously from about 1.2 mm to about 0.20 mm and lower;especially still more advantageously from about 1.0 mm to about 0.25 mmand lower.

The gels made from higher viscosity copolymers (i) are resistant tobreaking when sheared than triblock copolymer gels. This can bedemonstrated by forming a very soft gel, for example 100 parts copolymerto 800 parts plasticizing oil. The soft gel is cut into a strip of 2.5cm×2.5 cm cross-section, the gel strip is gripped lengthwise tightly inthe left hand about its cross-section and an exposed part of the gelstrip being gripped lengthwise around its cross-section tightly by theright hand as close to the left hand as possible without stretching.With the two hands gripping the gel strip's cross-section, the hands aremoved in opposite directions to shear apart the gel strip at itscross-section. The shearing action by the gripping hands is done at thefastest speed possible as can be performed by human hands. The shearingaction is performed at a fraction of a second, possible at about 0.5seconds. Using this demonstration, the copolymer (I) gels will noteasily break completely apart as would gels formed from triblockcopolymers. In some cases, it will take two, three, or more attempts toshear a high viscosity copolymer (I) gel strip this way. Whereas, alower viscosity triblock copolymer gel strip can be sheared apart on thefirst try. For gels made from copolymers with viscosities of 5 wt %solution in Toluene, their shear resistance will decrease withdecreasing viscosity. For example, the shear strengths as tested by handshearing described above of gels made from copolymers having viscositiesof 150, 120, 110, 105, 95, 90, 89, 85, 70, 60, 58, 48, 42, 40, 35, 28,27, 25, 21 cps, and the like can be expected to decrease with decreasingviscosity.

The tensile strengths of multiblock copolymer gels made from higherviscosity copolymers (I) can be slightly lower than or equal to thetensile strengths of gels made from lower solution viscosity triblockcopolymers (II).

Strands of gels comprising higher viscosity multiblock copolymers willperform better than gel strands made from gels of lower viscositytriblock copolymers when used in flossing amalgam molars and more thanthree times better when used in flossing front teeth.

Gels, in general, will exhibit higher tensile and greater tearresistance than their parent gels containing higher concentrations ofplasticizer.

As compared to spongy nylon, regular waxed nylon, and extra fine unwaxednylon when flossing amalgam molars, the performance of multiblockcopolymer gels are on the average substantially better.

While advantageous components and formulation ranges based on thedesired properties of the multiblock copolymer gels nave been disclosedherein. Persons of skill in the art can extend these ranges usingappropriate material according to the principles discussed herein. Allsuch variations and deviations which rely on the teachings through whichthe present invention has advanced the art are considered to be withinthe spirit and scope of the present invention.

The invention is further illustrated by means of the followingillustrative embodiments, which are given for purpose of illustrationonly and are not meant to limit the invention to the particularcomponents and amounts disclosed.

EXAMPLE I

Gels of 100 parts of high viscosity linear Kraton G1651 (amorphousS-EB-S), Septon 8006 (amorphous S-EB-S), Kraton GRP6918 (SEPS) and ahigh viscosity radial amorphous midblock segment (SEB)_(n) triblockcopolymers and 800, 600, 500, 450, 300, 250 parts by weight of Duraprime200 white oil (plasticizer) are melt blended and samples molded, thebulk gel rigidities are found to be within the range of 2 to 1,800 gramBloom and the tensile strength, notched tear strength, and resistance tofatigue are found to decrease with increase amounts of plasticizers andunsuitable for use as floss.

EXAMPLE II

Gels of 100 parts of high viscosity linear (S-EB-S), (S-EP-S),(S-B-EP-S), (S-B-EB-S) (S-B-EP-B-S), (S-B-EB-B-S), (S-B-EB-EP-S),(S-B-EP-EB-S), (S-EB-EP-S), and (S-EP-B-EP-S) block copolymers and 800,600, 500, 450, 300, 250 parts by weight of Duraprime 200 white oil(plasticizer) are each melt blended and samples molded, the bulk gelrigidities are found to be within the range of 2 to 1,800 gram Bloom andthe tensile strength, notched tear strength, and resistance to fatigueare found to decrease with increase amounts of plasticizers andunsuitable for use as floss.

EXAMPLE III

Gels of 100 parts of high viscosity linear (S-EB₂₅ -EP-S), (S-E-EB₂₅ -S)(S-EP-E-EP-S), (S-E-EB-S), (S-E-EP-S), (S-E-EP-E-S), (S-E-EB-B-S),(S-E-EB-E-S), (S-E-B-EB-S), (S-E-B-EP-S), (S-E-EB-EP-S), (S-E-EP-EB-S),(S-E-EP-E-EP-S), (S-E-EP-E-EB-S), (S-E-EB-B-EP-S), (S-E-EP-B-EB-S),(S-E-EP-E-EP-E-S), (SE-EP-E-EB-S), (S-E-EP-E-EP-EB-S),(S-E-EP-E-EP-E-S), and (S-E-EP-EB-EP-EB-B-S) block copolymers and 800,600, 500, 450, 300, 250 parts by weight of Duraprime 200 white oil(plasticizer) are each melt blended and samples molded, the bulk gelrigidities are found to be within the range of 2 to 1,800 gram Bloom andthe tensile strength, notched tear strength, and resistance to fatigueand stress rupture are found to be greater than that of amorphous gelsof Example II and suitable for use as floss.

EXAMPLE IV

Example III is repeated using plasticizers L-14, L-50, L-100, H-15,H-25, H-35, H-50, H-100, H-300, L-14E, H-300E, Actipol E6, E16, E23,Kraton L-1203, EKP-206, EKP-207, HPVM-2203, Amoco C-60, Piccolyte S10,Duraprime (55, 70, 90, 200, 350, 400), Tufflo (6006, 6016, 6016M, 6026,6036, 6056, 6206) Bayol, Bernol, American, Blandol, Drakeol, Ervol,Gloria, and Kaydol, the bulk gel rigidities are found to be within therange of 2 gram to 1,800 gram Bloom and the tear resistance of themultiblock copolymers at corresponding rigidities are found to besubstantially higher than the tear resistance of the triblock copolymergels of EXAMPLES I or II.

EXAMPLE V

Example III is repeated using plasticizers L-14, L-50, L-100, H-15,H-25, H-35, H-50, H-100, H-300, L-14E, H-300E, Actipol E6, E16, E23,Kraton L-1203, EKP-206, EKP-207, HPVM-2203, Amoco C-60, Piccolyte S10,Duraprime (55, 70, 90, 200, 350, 400), Tufflo (6006, 6016, 6016M, 6026,6036, 6056, 6206,) Bayol, Bernol, American, Blandol, Drakeol, Ervol,Gloria, and Kaydol, the bulk gel rigidities are found to be within therange of 2 gram to 1,800 gram Bloom and the tear resistance of themultiblock copolymers at corresponding rigidities are found to besubstantially higher than the tear resistance of the triblock copolymergels of EXAMPLE I or II.

EXAMPLE VI

A gel composition of 100 parts of Kuraray's S-E-EP-S 4055 copolymer and400 parts by weight of Duraprime 200 white oil was made followingExample I and extruded and drawn (from a 7.15 mm diameter orifice) intoa strand of uniform diameter onto a take-up roll of continuous lengths.The strand diameter was varied by increasing and decreasing the speed ofthe take-up roll. The continuous strand of varying diameter gel strandwas cut to suitable lengths for use and testing as dental floss.Additional gel was also casted in varying thickness and tested. Theresults of samples tested are shown in Table 3, #4-7; Table 4, #12-15and 20; Table 5 #22, 23, 27-29; Table 6 #36-32; Table 7, #40-43, #76 and77. Sample Nos. 76 and 77 were tested together. Sample 77 exhibitedhigher tensile strength after 27.75% of plasticizing oil was extracted(with 2.89 parts by weight of oil remaining), its rigidity remainedsubstantially unchanged.

EXAMPLE VII

A gel composition of 100 parts of Kraton G1651 and 400 parts by weightof Duraprime 200 white oil was made following Example I and extruded anddrawn (from a 7.15 mm diameter orifice) into a strand of uniformdiameter onto a take-up roll of continuous lengths. The strand diameterwas varied by increasing and decreasing the speed of the take-up roll.The continuous strand of varying diameter gel strand was cut to suitablelengths for use and testing as dental floss. Additional gel was alsocasted in varying thickness and tested. The results of samples testedare shown in Table 3B, #8-11; Table 4, #16-19 and 21; Table 5, #24-26;Table 6, #33-35; and Table 7, #36-39.

                  TABLE 3A                                                        ______________________________________                                        Flossing Cycles to Break                                                      Sample            cross-section                                                                           .sup.2 Floss amalgram                                                                    .sup.3 Floss                           No.   Floss Type  size      molars to  fronts                                 ______________________________________                                        1     .sup.4 Unwaxed                                                                            0.30      18         200+                                         spongy nylon                                                            2     .sup.5 Regular waxed                                                                      0.11      11         200+                                         nylon                                                                   3     .sup.6 Extra fine                                                                         0.06       6         200+                                         unwaxed nylon                                                           ______________________________________                                    

                  TABLE 3B                                                        ______________________________________                                        Flossing Cycles to Break                                                      Sample          Relaxed/extended                                                                          .sup.2 Floss amalgram                                                                   .sup.3 Floss                            No.   Floss Type                                                                              dia. (mm)   molars to break                                                                         fronts to                               ______________________________________                                        4     .sup.7 Gel                                                                              2.42/0.16   37        76                                      5     .sup.7 Gel                                                                              2.63/0.17   29        83                                      6     .sup.7 Gel                                                                              2.75/0.17   36        183                                     7     .sup.7 Gel                                                                              2.83/0.20   20        74                                      8     .sup.8 Gel                                                                              3.22/0.22    8        30                                      9     .sup.8 Gel                                                                              2.48/0.31    4        20                                      10    .sup.8 Gel                                                                              3.16/0.33    6        44                                      11    .sup.8 Gel                                                                              2.86/0.24    5        29                                      ______________________________________                                    

¹ floss dimension relaxed state and when extended during flossingcycles. ² Test conditions: number of flossing cycles (before breaking)between amalgam alloy metal (fully contacting) lower, left first andsecond human back molars. ³ Test conditions: number of flossing cycles(before breaking) between upper human front teeth. ⁴ Oral-B UltraFloss™, interlocking network of spongy nylon floss. ⁵ Johnson & Johnsonregular waxed nylon floss. ⁶ Johnson & Johnson extra fine unwaxed nylonfloss. ⁷ Gel made from 100 parts by weight of S-E-EP-S 4055 multiblockcopolymer having a Brookfield viscosity of 90 as measured for a 5 wt %solution in toluene at 30° C. and 400 parts by weight of Duraprime 200plasticizing oil. ⁸ Gel made from 100 parts by weight of SEBS KratonG1651 copolymer having a Brookfield viscosity of 40 as measured for a 5wt % solution in toluene at 30° C. ²,3 Any selected test methods may beutilized in testing the floss performance of the gels. For example, aset of simulated upper front teeth fully contacting under a uniformspring load of two pounds may be used in place of human teeth. Suchsimulated testing conditions may be more severe than conditions 2 andless severe than conditions 3 above.

                  TABLE 4                                                         ______________________________________                                        Tensile Strength of Gel Strands                                               Sample                                                                              Number of Radius    Area  Failure Tensile                               No.   Strands   (mm)      (cm.sup.2)                                                                          (Kg)    (Kg/cm.sup.2)                         ______________________________________                                        12.sup.                                                                             3         1.325     0.165 9.00    54.54                                 13.sup.                                                                             4         1.250     0.196 9.50    48.39                                 14.sup.                                                                             4         1.421     0.253 9.50    37.44                                 15.sup.                                                                             5         1.359     0.290 12.5    43.08                                 16.sup.                                                                             2         2.14      0.287 14.0    48.78                                 17.sup.                                                                             2         1.55      0.151 11.5    75.95                                 18.sup.                                                                             2         1.17      0.086 8.50    98.84                                 19.sup.                                                                             2         1.322     0.109 9.0     81.96                                 20.sup.                                                                             6         1.375     0.356 14      39.32                                 21.sup.                                                                             2         1.445     0.131 10      76.33                                 76.sup.                                                                             1         1.22      0.0467                                                                              2.00    42.82                                 77.sup.†                                                                     1         1.38      0.0598                                                                              4.00    66.88                                 ______________________________________                                         .sup.† Plasticizing oil extracted                                 

                  TABLE 5                                                         ______________________________________                                        Tensilke Strength of Bulk Gels Samples                                        Sample   Cross-section  Failure Tensile                                       No.      (cm2)          (Kg)    (Kg/cm2)                                      ______________________________________                                        22       1.96           24.0    12.24                                         23       1.56           25.0    16.02                                         24       0.58           15.0    25.83                                         25       0.602          16.0    26.54                                         26       1.163          24.0    20.64                                         27       0.913          21.0    23.00                                         28       0.595          18.5    36.56                                         29       0.702          19.0    27.06                                         ______________________________________                                    

                  TABLE 6                                                         ______________________________________                                        180° U Bend Tear Propagation of Bulk Gels Samples                      Sample   Tear width    Failure Tear Force                                     No.      (cm)          (Kg)    (Kg/cm)                                        ______________________________________                                        30       1.31          2.75    2.09                                           31       1.28          3.0     2.30                                           32       1.14          2.75    2.56                                           33       1.53          2.75    1.79                                           34       1.27          2.25    1.76                                           35       1.26          2.25    1.77                                           ______________________________________                                    

                  TABLE 7                                                         ______________________________________                                        Notched Gel Strand Tension Tear Propagation                                   Sample   Strand Dia.   Failure Tear Force                                     No.      (mm)          (Kg)    (Kg/cm)                                        ______________________________________                                        36       2.86          0.75    2.62                                           37       2.49          0.75    3.01                                           38       3.09          0.60    1.94                                           39       2.62          0.70    2.67                                           40       2.54          0.60    2.36                                           41       1.94          1.10    5.67                                           42       1.58          0.75    4.74                                           43       2.34          1.2     5.12                                           ______________________________________                                    

The tensile strengths of gels made from higher viscosity copolymers arelower than the tensile strengths of gels made from lower solutionviscosity copolymers. This was later found to be due to orientationeffects and not considered significant.

The tear resistance of gels made from higher viscosity copolymers arehigher than the tear resistance of gels made from lower solutionviscosity copolymers.

Gel strands made from higher viscosity copolymers perform better thangel strands made of lower viscosity copolymers when used in flossingamalgam molars and more than three times better when used in flossingfront teeth.

As compared to spongy nylon, regular waxed nylon, and extra fine unwaxednylon when flossing amalgam molars, the performance of gels are on theaverage substantially better.

Examples below illustrate other modes of practice contemplated.

EXAMPLE VIII

Gels of 100 parts of linear high content butylene (S-EB-S) and highcontent isopropylethyene (S-EP-S) block copolymers and 800, 600, 500,450, 300, 250 parts by weight of Duraprime 200 white oil (plasticizer)are each melt blended in admixture with the gels of Example III andsamples molded, the bulk gel rigidities are found to be within the rangeof 2 to 1,800 gram Bloom and the tensile strength, notched tearstrength, and resistance to fatigue and stress rupture are found to begreater than that of amorphous gels of Example II and suitable for useas floss.

The gels are especially advantageously useful when subjected toconditions of stretching, shearing, and tearing during flossing. Thegels useful for flossing are characterized by low rigidities and highsolution viscosity of the gels made from multiblock copolymers havingtwo or more midblock polymer chains.

Tables 8-10 are illustrative in meeting one or more of the criteriadetailed above.

    __________________________________________________________________________    8. Illustrative Modes of Practice Contemplated                                for multiblock copolymer Gels                                                        5 Wt % Copolymer   Number of                                           100 Parts by                                                                         Viscosity                                                                              Sty-                                                                              Parts by Wt                                                                         floss cycles                                                                        Sample                                        wt     (cps)    rene %                                                                            of Oil                                                                              to break                                                                            No.                                           __________________________________________________________________________    S-E-EP-S                                                                             90       30  300   30+   44                                            S-E-EP-E-S                                                                           60       30  300   30+   45                                            (S-E-EP)n                                                                            240      35  300   30+   46                                            (S-E-EP-E)n                                                                          240      35  300   30+   47                                            S-B-EP-S                                                                             90       30  300   30+   48                                            S-E-EB-S                                                                             90       35  300   30+   49                                            S-EB-EP-S                                                                            90       30  300   30+   50                                            S-E-EP-EP-S                                                                          90       30  300   30+   51                                            __________________________________________________________________________

                                      TABLE 9                                     __________________________________________________________________________    Illustrative Modes of Practice Contemplated                                   for multiblock copolymer Gels                                                         Wt % Copolymer     Number Floss                                               Viscosity                                                                              Sty-                                                                              Parts by Wt                                                                         cycles to                                                                            Sample                                      100 Parts by wt                                                                       (cps)    rene %                                                                            of Oil                                                                              Break  No.                                         __________________________________________________________________________    S-E-EP-EB-S                                                                           120      33  250   30+    52                                          S-E-EP-EP-S                                                                           120      33  250   30+    53                                          (S-B-EP)n                                                                             380      35  250   30+    54                                          (S-E-EB)n                                                                             380      35  250   30+    55                                          S-E-EP-E-EP-S                                                                         120      30  250   30+    56                                          S-E-EP-P-S                                                                            120      35  250   30+    57                                          S-E-B-EP-S                                                                            120      30  250   30+    58                                          S-E-EP-EP-E-S                                                                         120      30  250   30+    59                                          __________________________________________________________________________

                                      TABLE 10                                    __________________________________________________________________________    Illustrative Modes of Practice Contemplated                                   for multiblock copolymer (0.5-2.0 cm                                          diameters) Gel Strands                                                                5 Wt % Copolymer                                                              Viscosity                                                                              Styrene                                                                           Parts by Wt                                                                         # Floss cycles                                                                       Sample                                      100 Parts by wt                                                                       (cps)    %   of Oil                                                                              to Break                                                                             No.                                         __________________________________________________________________________    S-E-EP-S                                                                              40       30  350   30+    60                                          S-E-EP-S                                                                              60       30  350   30+    61                                          (S-E-EP-EB)n                                                                          340      30  350   30+    62                                          (S-E-EP-EP-E)n                                                                        340      30  350   30+    63                                          S-E-EP-E-EP-E-S                                                                       90       30  350   30+    64                                          S-EB-EP-EP-S                                                                          90       35  350   30+    65                                          S-B-EB-B-S                                                                            90       30  350   30+    66                                          S-E-EP-EP-E-S                                                                         90       30  350   30+    67                                          __________________________________________________________________________

While certain features of this invention have been described in detailwith respect to various embodiments thereof, it will, of course, beapparent that other modifications can be made within the spirit andscope of this invention, and it is not intended to limit the inventionto the exact details shown above except insofar as they are defined inthe following claims.

What I claim is:
 1. An improved dental floss comprising: a soft,flexible, high strength, high tear resistant, and high stress ruptureresistant crystal gel, in the shape of a strand, a thread, a strip, aband, a yarn, a tape, or a sheet of film for flossing teeth, said sheethaving a selected shaped peripheral edge of selective thickness and atleast two holes positioned at a selected distance apart through saidfilm and at a selective distance away from said edge, each of said holesbeing a size suitable for insertion therethrough by one or more fingersof one or both hands for positioning said fingers through said filmwithout substantial constriction of blood flow in said fingers; saidholes with said fingers therethrough by allowing said fingers tomanipulate said film and said shaped peripheral edge for:a) providingopposing inserted fingers of each hand to extend substantially taught amajor lengths of said shaped peripheral edge by opposing insertedfingers pulling in opposite direction; b) providing freedom of one ormore fingers including thumbs and forefingers of one or both of saidhands to grip, pull, push, deform, guide, fold or otherwise manipulate alength of said shaped peripheral edge between said teeth duringflossing; c) said sheet about said shaped peripheral edge suitable ofbeing: extended taught for flossing) said teeth having a tight teethgap, or folded into a thicker extended film layer for flossing saidteeth having a wide or loose teeth gap; said crystal gel comprising:(I)100 parts by weight of one or more linear, branched, radial,star-shaped, multi-arm or branched block copolymers or mixtures of twoor more said block copolymers, said copolymers having at least onesubstantially crystalline polyethylene midblocks, (II) selected amountsof a plasticizing oil sufficient to achieve a gel rigidity of about 2gram Bloom to about 1,800 gram Bloom, said (I) copolymers in combinationwith or without a selected amount of (III) one or more of a selectedpolymer, copolymer or resin, andwhen said (I) copolymers comprises onemidblock, said (I) copolymer is of the formula comprising (i):poly(styrene-ethylene-styrene) or poly(styrene-ethylene)_(n), or whensaid (I) copolymer comprises two or more midblocks, said (I) copolymeris of the formula comprising (ii):poly(styrene-ethylene-ethylene-propylene-styrene),poly(styrene-ethylene-ethylene-butylene-styrene),poly(styrene-ethylene-ethylene-popylene-ethylene-butylene-styrene-poly(styrene-ethylene-ethylene-propylene-ethylene-styrene),poly(styrene-ethylene-ethylene-propylene-ethylene-ethylene-proplene-ethylene-styrene),poly(styrene-ethylene-ethylene-butylene)_(n),poly(styrene-ethylene-ethylene-propylene)_(n),poly(styrene-ethylene-ethylene-propylene-ethylene)_(n),poly(styrene-ethylene-ethylene-propylene-ethylene-ethylene-propylene).sub.n,orpoly(styrene-ethylene-ethylene-propylene-ethylene-ethylene-propylene-ethylene)_(n),wherein n is a number greater than two; said crystalline polyethylenemidblocks being formed from hydrogenation of sufficient amounts of 1,4poly(butadiene) midblocks which is capable of exhibiting a meltingendotherm in differential scanning calorimeter curves of about 20° C. toabout 75° C.; with the proviso that when said gel comprises one or more(i) copolymers, said gel is a mixture of (i) copolymers in combinationwith one or more (ii) copolymers or with one or more substantiallyamorphous midblock block copolymers: said (III) polymer, copolymer, orresin being poly(styrene-butadiene-styrene), poly(styrene-butadienel,poly(styrene-isoprene-styrene), poly-styrene-isoprene),poly(styrene-ethylene-propylene),poly(styrene-ethylene-propylene-styrene),poly(styrene-ethylene-butylene-styrene), low viscositypoly(styrene-ethylene-butylene-styrene),poly(styrene-ethylene-butylene), poly(styrene-ethylene-propylene)n,poly(styrene-ethylene-butylene)n, polystyrene, polybutylene,poly(ethylene-propylene), poly(ethylene-butylene), polypropylene,polyethylene, polymerized mixed olefins, polyterpene, glycerol ester ofrosin, pentaerythritol ester of rosin, saturated alicyclic hydrocarbon,coumarone indene, hydrocarbon, mixed olefin, alkylated aromatichydrocarbon polyalphamethylstyrene/vinyl toluene copolymer, or a lowviscosity polystyrene; wherein said selected copolymer is a linear,branched or star-shaped, or multiarm copolymer.
 2. A floss according toclaim 1, wherein said crystal gel is capable of exhibiting a meltingendotherm in differential scanning calorimeter, DSC, curves of about 25°C. to about 80° C.
 3. A floss comprising: a soft, flexible, highstrength, high tear resistant, and high stress rupture resistant crystalgel in the shape of a strand, a thread, a strip, a band, a yarn, a tape,or a sheet of film for flossing teeth and massaging gums which isnon-lacerating to the gums and having a softness as determined by gelrigidity substantially matching the rigidity of said gums, said crystalgel made from one or more block copolymers having one or morecrystalline polyethylene midblocks which copolymer is capable ofexhibiting a melting endotherm as determined by differential scanningcalorimeter curves of about 20° C. to about 75° C.
 4. A flosscomprising: a soft, flexible, high strength, high tear resistant, andhigh stress rupture resistant crystal gel in the shape of a strand, atape, or a sheet of film for flossing teeth and massaging gums which isnon-lacerating to the gums and having a softness as determined by gelrigidity less than the rigidity of said gums, said crystal gel made fromone or more block copolymers having one or more crystalline polyethylenemidblocks which copolymer is capable of exhibiting a melting endothermas determined by differential scanning calorimeter curves of about 20°C. to about 75° C.
 5. A floss comprising: a soft, flexible, highstrength, high tear resistant, and high stress rupture resistant crystalgel in the shape of a strand, a tape, or a sheet of film for flossingteeth and massaging gums which is non-lacerating to the gums and havinga softness as determined by gel rigidity not substantially greater thanthe rigidity of said gums, said crystal gel made from one or more blockcopolymers having one or more crystalline polyethylene midblocks whichcopolymer is capable of exhibiting a melting endotherm as determined bydifferential scanning calorimeter curves of about 20° C. to about 75° C.6. A floss comprising: a soft and flexible crystal gel in the shape of astrand, a tape, or a sheet of film for flossing teeth and massaging gumswhich exhibits higher tensile strength, higher tear resistance, orhigher stress rupture resistance than gels made from amorphousstyrene-ethylene-butylene-styrene or styrene-ethylene/propylene-styreneblock copolymers, said crystal gel made from one or more blockcopolymers having one or more crystalline polyethylene midblocks whichcopolymer is capable of exhibiting a melting endotherm as determined bydifferential scanning calorimeter curves of about 20° C. to about 75° C.7. A floss comprising: a soft and flexible crystal gel in the shape of astrand, a thread, a strip, a band, a yarn, a tape, or a sheet of filmfor flossing teeth and massaging gums which exhibits higher tearresistance as determined by a higher flossing cycles to break than gelsmade from amorphous styrene-ethylene-butylene-styrene orstyrene-ethylene/propylene-styrene block copolymers, said crystal gelmade from one or more block copolymers having one or more crystallinepolyethylene midblocks which copolymer is capable of exhibiting amelting endotherm as determined by differential scanning calorimetercurves of about 20° C. to about 75° C.
 8. A floss comprising: a soft andflexible crystal gel in the shape of a strand, a thread, a strip, aband, a yarn, a tape, or a sheet of film for flossing teeth andmassaging gums which exhibits higher stress rupture resistance asdetermined by a higher flossing cycles to break than gels made fromamorphous styrene-ethylene-butylene-styrene orstyrene-ethylene/propylene-styrene block copolymers, said crystal gelmade from one or more block copolymers having one or more crystallinepolyethylene midblocks which copolymer is capable of exhibiting amelting endotherm as determined by differential scanning calorimetercurves of about 20° C. to about 75° C.
 9. A crystal gel comprising:(I)100 parts by weight of one or more linear, branched, radial,star-shaped, multi-arm or branched block copolymers or mixtures of twoor more said copolymers, said copolymers having at least onesubstantially crystalline polyethylene midblocks, (II) a selectedamounts of a plasticizing oil sufficient to achieve a gel rigidity ofabout 2 gram Bloom to about 1,800 gram Bloom, said (I) copolymers incombination with or without a selected amount of (III) one or more of aselected polymer, copolymer or resin, andwhen said (I) copolymerscomprises one midblock, said copolymer is of the formula comprising (i):poly(styrene-ethylene-styrene) or poly(styrene-ethylene)_(n), or whensaid (I) copolymer comprises two or more midblocks, said copolymer is ofthe formula comprising (ii):poly(styrene-ethylene-ethylene-propylene-styrene),poly(styrene-ethylene-ethylene-butylene-styrene),poly(styrene-ethylene-ethylene-popylene-ethylene-butylene-styrene),poly(styrene-ethylene-ethylene-propylene-ethylene-styrene),poly(styrene-ethylene-ethylene-propylene-ethylene-ethylene-propylene-ethylene-styrene),poly(styrene-ethylene-ethylene-butylene)_(n),poly(styrene-ethylene-ethylene-propylene)_(n),poly(styrene-ethylene-ethylene-propylene-ethylene)_(n),poly(styrene-ethylene-ethylene-propylene-ethylene-ethylene-propylene).sub.n,orpoly(styrene-ethylene-ethylene-propylene-ethylene-ethylene-propylene-ethylene)_(n),wherein n is a number greater than two; said crystalline polyethylenemidblocks being formed from hydrogenation of sufficient amounts of 1,4poly(butadiene) midblocks which is capable of exhibiting a meltingendotherm in differential scanning calorimeter curves of about 20° C. toabout 75° C.; with the proviso that when said gel comprises one or more(i) copolymers, said gel is a mixture of (i) copolymers in combinationwith one or more (ii) copolymers or with one or more substantiallyamorphous midblock block copolymers; said (III) polymer, copolymer, orresin being poly(styrene-butadiene-styrene), poly(styrene-butadiene),poly(styrene-isoprene-styrene), poly(styrene-isoprene),poly(styrene-ethylene-propylene),poly(styrene-ethylene-propylene-styrene),poly(styrene-ethylene-butylene-styrene), low viscositypoly(styrene-ethylene-butylene-styrene),poly(styrene-ethylene-butylene), poly(styrene-ethylene-propylene)n,poly(styrene-ethylene-butylene)n, polystyrene, polybutylene,poly(ethylene-propylene), poly(ethylene-butylene), polypropylene,polyethylene, polymerized mixed olefins, polyterpene, glycerol ester ofrosin, pentaerythritol ester of rosin, saturated alicyclic hydrocarbon,coumarone indene, hydrocarbon, mixed olefin, alkylated aromatichydrocarbon, polyalphamethylstyrene/vinyl toluene copolymer, or a lowviscosity polystyrene; wherein said selected copolymer is a linear,branched or star-shaped, or multiarm copolymer.
 10. A crystal gel ofclaim 9 in the form of a thread, a tape, a band, a yarn, or a sheet offilm.
 11. A crystal gel of claim 9 in the form of a thread, a tape, aband, a yarn, or a sheet of film; wherein said gel having a gel rigidityof greater than 1,800 gram Bloom.
 12. A crystal gel comprising:(I) 100parts by weight of one or more linear, branched, radial, star-shaped,multi-arm or branched block copolymers or mixtures of two or more saidcopolymers, said copolymers having at least one substantiallycrystalline polyethylene midblocks, (II) a selected amounts of aplasticizing oil sufficient to achieve a gel rigidity of about 2 gramBloom to about 1,800 gram Bloom; said (I) copolymers in combination withor without a selected amount of (III) one or more of a selected polymer,copolymer or resin, andwhen said (I) copolymers comprises one midblock,said copolymer is of the formula comprising (i):poly(styrene-ethylene-styrene) or poly(styrene-ethylene)_(n), or whensaid (I) copolymer comprises two or more midblocks, said copolymer is ofthe formula comprising (ii):poly(styrene-ethylene-ethylene-butylene-styrene),poly(styrene-ethylene-ethylene-popylene-ethylene-butylene-styrene),poly(styrene-ethylene-ethylene-propylene-ethylene-styrene),poly(styrene-ethylene-ethylene-propylene-ethylene-ethylene-propylene-ethylene-styrene),poly(styrene-ethylene-ethylene-butylene)_(n),poly(styrene-ethylene-ethylene-propylene)_(n),poly(styrene-ethylene-ethylene-propylene-ethylene)_(n),poly(styrene-ethylene-ethylene-propylene-ethylene-ethylene-propylene).sub.n,orpoly(styrene-ethylene-ethylene-propylene-ethylene-ethylene-propylene-ethylene)_(n),wherein n is a number greater than two; said crystalline polyethylenemidblocks being formed from hydrogenation of sufficient amounts of 1,4poly(butadiene) midblocks which is capable of exhibiting a meltingendotherm in differential scanning calorimeter curves of about 20° C. toabout 75° C.; with the proviso that when said gel comprises one or more(i) copolymers, said gel is a mixture of (i) copolymers in combinationwith one or more (ii) copolymers or with one or more substantiallyamorphous midblock block copolymers; said (III) polymer, copolymer, orresin being poly(styrene-butadiene-styrene), poly(styrene-butadiene),poly(styrene-isoprene-styrene), poly(styrene-isoprene),poly(styrene-ethylene-propylene),poly(styrene-ethylene-propylene-styrene),poly(styrene-ethylene-butylene-styrene), low viscositypoly(styrene-ethylene-butylene-styrene),poly(styrene-ethylene-butylene), poly(styrene-ethylene-propylene)n,poly(styrene-ethylene-butylene)n, polystyrene, polybutylene,poly(ethylene-propylene), poly(ethylene-butylene), polypropylene,polyethylene, polymerized mixed olefins, polyterpene, glycerol ester ofrosin, pentaerytritol ester of rosin, saturated alicyclic hydrocarbon,coumarone indene, hydrocarbon, mixed olefin, alkylated aromatichydrocarbon, polyalphamethylstyrene/vinyl toluene copolymer, or a lowviscosity polystyrene; wherein said selected copolymer is a linear,branched or star-shaped, or multiarm copolymer.
 13. A crystal gel ofclaim 12 in the form of a thread, a tape, a band, a yarn, or a sheet offilm.
 14. A crystal gel of claim 12 in the form of a thread, a tape, aband, a yarn, or a sheet of film; wherein said gel having a gel rigidityof greater than 1,800 gram Bloom.